[PATCH v18 00/18]Timestamp synchronization of host - guest tracing session

[PATCH v18 00/18]Timestamp synchronization of host - guest tracing session

[Tzvetomir Stoyanov (VMware)]

Basic infrastructure for host - guest timestamp synchronization and a
POC implementation of PTP-like algorithm. 

[
 v18 changes: addressed Steven Rostdet comments:
  - Replaced semaphores with pthread mutexes.
  - Made bitmask with time sync protocols unlimited, so we can support
    more than 32 protocols. That required to redesign the trace request
    packet format.
  - A lot of small fixes.
	
 v17 changes:
  - Implemented new PTP logic for calculating the clocks offset, using
    histogram of all PTP samples. It gives better results than the logic
    with the fastest response time, so set the new one as default in the
    POC patch.

 v16 changes:
  - Fixed compilation in case no VSOCK is available (Thanks to Slavomir Kaslev)
  - Fixed a typo in trace-cmd-record.1.txt (Thanks to Slavomir Kaslev)
  - Added forgotten file in the patch "trace-cmd: Add new library APIs for
    ftrace instances." - trace-instance.c
  - Fixed few compilation warnings related to TSYNC_DEBUG code.
  - Removed a blank line at the end of "tsync_readme" file. 

 v15 changes:
  - Removed the patch for "--proc-map" from the series, as it should not
    be part of it.

 v14 changes:
  - Bring back the PTP-like algorithm and removed the ftrace event based logic.
  - Reimplemented the PTP-like algorithm to use raw ftrace markers, instead of clock_gettime() API.
  - Refactored the logic to be algorithm independent and plugin friendly.
  - Implemented continuous timestamps synchronization, while the trace is running.
  - Moved logic from trace-cmd application to libtracecmd, as new library APIs.
  - Implemented new trace id functionality.
  - Implemented new guest section in host trace.dat file.
	
 v13 changes:
  - Remove few patches from the set, as they were merged.
  - Rebased to the latest master, Slavomirs patchest "Add VM kernel tracing over
    vsockets and FIFOs" got merged!
 	
 v12 changes:
  - Rebased on top of Slavomir's v13 "Add VM kernel tracing over vsockets and FIFOs"

 v11 changes:
  - Rebased on top of Slavomir's v10 "Add VM kernel tracing over vsockets and FIFOs"
  - Addressed Slavomir's commnents from version 10 of the patch series.

 v10 changes:
  - Fixed broken compilation, call to timestamp_correction_calc() in timestamp_correct
    was smashed.
  - Replaced deprecated tep_data_event_from_type() API with tep_find_event().
  - Fixed a warning on assignment const to non const.

 v9 changes:
  - Fixed implementation of binary search algorithm in timestamp_correct()

 v8 changes:
  - Added rmdir() call in tracecmd_remove_instance(), to completely remove the instance. 
  However, there is an issue with deleting the instances using rmdir(), which is investigated.
  - Few changes in read_qemu_guests_pids(), timestamp_correct(), tsync_offset_load() 
 tracecmd_clock_context_new() and find_raw_events() suggested by Slavomir. 

 v7 changes:
  - Added warning messages in case time synchronization cannot be negotiated or fails.
  - Few optimizations and checks in read_qemu_guests_pids(), tsync_offset_load(),
    and find_raw_events(), suggested by Slavomir Kaslev.
  - Reworked timestamp_correct() to not use static variables.
  - Check TRACECMD_OPTION_TIME_SHIFT before reading time sync samples from the trace.dat file

 v6 changes:
  - Refactored tracecmd_msg_snd_time_sync() and tracecmd_msg_rcv_time_sync() functions:
    removed any time sync calculations logic as separate functions in trace-timesync.c file
  - Defined TSYNC_PROBE, TSYNC_REQ and TSYNC_RESP messages, in order to make the time sync
    protocol comprehensible.
  - Addressed Steven Rostedt comments.
  - Addressed Slavomir Kaslev commnets.

v5 changes:
  - Rebased to Slavomir's v8 "Add VM kernel tracing over vsockets and FIFOs"
    patch series.
  - Implemented an algorithm for time drift correction.
  - Addressed Slavomir's commnets.
  - Refactored the code: moved all time sync specific implementation in trace-timesync.c
  - Isolated all hardcoded event specific stuff in a structure, so it could be easily
    moved to external plugins.
  - Added a check for VSOCK support: do not perform vsock dependent time synchronisation
    in case there is no VSOCK support.

 v4 changes:
  - Removed the implementation of PTP-like algorithm. The current
    logic relies on matching time stamps of kvm_exit/virtio_transport_recv_pkt
    events on host to virtio_transport_alloc_pkt/vp_notify events on guest.
  - Rebased to Slavomir's v7 "Add VM kernel tracing over vsockets and FIFOs"
    patch series.
  - Decreased the time synch probes from 5000 to 300.
  - Addressed Steven Rostedt comments.
  - Code cleanup.

 v3 changes:
 - Removed any magic constants, used in the PTP-like algorithm,
   as Slavomir Kaslev suggested.
 - Implemented new algorithm, based on mapping kvm_exit events
   in host context to vsock_send events in guest context,
   suggested by Steven Rostedt.

 v2 changes:
  - Addressed Steven Rostedt comments.
  - Modified PTP-like timestamps sync algorithm to gain more accuracy, with the
    help of Yordan Karadzhov and Slavomir Kaslev.
]

Tzvetomir Stoyanov (7):
  trace-cmd: Implement new lib API: tracecmd_local_events_system()
  trace-cmd: Add support for negative time offsets in trace.dat file
  trace-cmd: Add implementations of htonll() and ntohll()
  trace-cmd: Add new library APIs for ftrace instances.
  trace-cmd: Find and store pids of tasks, which run virtual CPUs of
    given VM
  trace-cmd: Implement new API tracecmd_add_option_v()
  trace-cmd: Implement new option in trace.dat file:
    TRACECMD_OPTION_TIME_SHIFT

Tzvetomir Stoyanov (VMware) (11):
  trace-cmd: Add new library API for local CPU count
  trace-cmd: Add new library API for reading ftrace buffers
  trace-cmd: Add new API to generate a unique ID of the tracing session
  trace-cmd: Store the session tracing ID in the trace.dat file
  trace-cmd: Exchange tracing IDs between host and guest
  trace-cmd: Add guest information in host's trace.dat file
  trace-cmd: Add host trace clock as guest trace argument
  trace-cmd: Refactor few trace-cmd internal functions.
  trace-cmd: Basic infrastructure for host - guest timestamp
    synchronization
  trace-cmd: [POC] PTP-like algorithm for host - guest timestamp
    synchronization
  trace-cmd: Debug scripts for PTP-like algorithm for host - guest
    timestamp synchronization

 Documentation/trace-cmd-record.1.txt      |   7 +
 include/trace-cmd/trace-cmd.h             | 121 +++-
 include/trace-cmd/trace-msg.h             |  10 +
 include/traceevent/event-parse.h          |   1 +
 lib/trace-cmd/Makefile                    |   3 +
 lib/trace-cmd/include/trace-cmd-local.h   |  33 +-
 lib/trace-cmd/include/trace-tsync-local.h |  38 ++
 lib/trace-cmd/trace-input.c               | 323 ++++++++++-
 lib/trace-cmd/trace-instance.c            | 335 +++++++++++
 lib/trace-cmd/trace-msg.c                 | 403 ++++++++++++--
 lib/trace-cmd/trace-output.c              | 117 +++-
 lib/trace-cmd/trace-timesync-ptp.c        | 649 ++++++++++++++++++++++
 lib/trace-cmd/trace-timesync.c            | 504 +++++++++++++++++
 lib/trace-cmd/trace-util.c                | 374 +++++++++++--
 scripts/debug/tsync_hist.py               |  57 ++
 scripts/debug/tsync_readme                |  12 +
 scripts/debug/tsync_res.py                |  46 ++
 tracecmd/Makefile                         |   3 +-
 tracecmd/include/trace-local.h            |  33 +-
 tracecmd/trace-agent.c                    |  58 +-
 tracecmd/trace-list.c                     |   2 +-
 tracecmd/trace-profile.c                  |   2 +-
 tracecmd/trace-read.c                     |   4 +-
 tracecmd/trace-record.c                   | 612 ++++++++++----------
 tracecmd/trace-show.c                     |   2 +
 tracecmd/trace-stat.c                     |  24 +-
 tracecmd/trace-tsync.c                    | 271 +++++++++
 tracecmd/trace-usage.c                    |   4 +
 28 files changed, 3563 insertions(+), 485 deletions(-)
 create mode 100644 lib/trace-cmd/include/trace-tsync-local.h
 create mode 100644 lib/trace-cmd/trace-instance.c
 create mode 100644 lib/trace-cmd/trace-timesync-ptp.c
 create mode 100644 lib/trace-cmd/trace-timesync.c
 create mode 100644 scripts/debug/tsync_hist.py
 create mode 100644 scripts/debug/tsync_readme
 create mode 100644 scripts/debug/tsync_res.py
 create mode 100644 tracecmd/trace-tsync.c

-- 
2.23.0

[PATCH v18 01/18] trace-cmd: Implement new lib API: tracecmd_local_events_system()

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

The new tracecmd lib API tracecmd_local_events_system() creates
a tep handler and initializes it with the events of the specified
subsystems. It can be used instead of tracecmd_local_events(), when
not all events are going to be parsed using that tep handler.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 include/trace-cmd/trace-cmd.h |   4 +-
 lib/trace-cmd/trace-util.c    | 102 +++++++++++++++++++++++-----------
 2 files changed, 72 insertions(+), 34 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 13afce7..9363a26 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -27,8 +27,10 @@ extern int tracecmd_disable_plugins;
 char **tracecmd_event_systems(const char *tracing_dir);
 char **tracecmd_system_events(const char *tracing_dir, const char *system);
 struct tep_handle *tracecmd_local_events(const char *tracing_dir);
+struct tep_handle *tracecmd_local_events_system(const char *tracing_dir,
+						const char * const *sys_names);
 int tracecmd_fill_local_events(const char *tracing_dir,
-			       struct tep_handle *pevent, int *parsing_failures);
+			       struct tep_handle *tep, int *parsing_failures);
 char **tracecmd_local_plugins(const char *tracing_dir);
 
 char **tracecmd_add_list(char **list, const char *name, int len);
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index b5bb0d5..e93225f 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -616,39 +616,20 @@ static int read_header(struct tep_handle *pevent, const char *events_dir)
 	return ret;
 }
 
-/**
- * tracecmd_local_events - create a pevent from the events on system
- * @tracing_dir: The directory that contains the events.
- *
- * Returns a pevent structure that contains the pevents local to
- * the system.
- */
-struct tep_handle *tracecmd_local_events(const char *tracing_dir)
+static bool contains(const char *name, const char * const *names)
 {
-	struct tep_handle *pevent = NULL;
-
-	pevent = tep_alloc();
-	if (!pevent)
-		return NULL;
-
-	if (tracecmd_fill_local_events(tracing_dir, pevent, NULL)) {
-		tep_free(pevent);
-		pevent = NULL;
-	}
-
-	return pevent;
+	if (!names)
+		return false;
+	for (; *names; names++)
+		if (strcmp(name, *names) == 0)
+			return true;
+	return false;
 }
 
-/**
- * tracecmd_fill_local_events - Fill a pevent with the events on system
- * @tracing_dir: The directory that contains the events.
- * @pevent: Allocated pevent which will be filled
- * @parsing_failures: return number of failures while parsing the event files
- *
- * Returns whether the operation succeeded
- */
-int tracecmd_fill_local_events(const char *tracing_dir,
-			       struct tep_handle *pevent, int *parsing_failures)
+static int tracecmd_fill_local_events_system(const char *tracing_dir,
+					     struct tep_handle *tep,
+					     const char * const *sys_names,
+					     int *parsing_failures)
 {
 	struct dirent *dent;
 	char *events_dir;
@@ -677,7 +658,7 @@ int tracecmd_fill_local_events(const char *tracing_dir,
 		goto out_free;
 	}
 
-	ret = read_header(pevent, events_dir);
+	ret = read_header(tep, events_dir);
 	if (ret < 0) {
 		ret = -1;
 		goto out_free;
@@ -690,7 +671,8 @@ int tracecmd_fill_local_events(const char *tracing_dir,
 		if (strcmp(name, ".") == 0 ||
 		    strcmp(name, "..") == 0)
 			continue;
-
+		if (sys_names && !contains(name, sys_names))
+			continue;
 		sys = append_file(events_dir, name);
 		ret = stat(sys, &st);
 		if (ret < 0 || !S_ISDIR(st.st_mode)) {
@@ -698,7 +680,7 @@ int tracecmd_fill_local_events(const char *tracing_dir,
 			continue;
 		}
 
-		ret = load_events(pevent, name, sys);
+		ret = load_events(tep, name, sys);
 
 		free(sys);
 
@@ -716,6 +698,60 @@ int tracecmd_fill_local_events(const char *tracing_dir,
 	return ret;
 }
 
+/**
+ * tracecmd_local_events_system - create a tep from the events of the specified subsystem
+ *
+ * @tracing_dir: The directory that contains the events
+ * @sys_name: Array of system names, to load the events from
+ * The last element from the array must be NULL
+ *
+ * Returns a tep structure that contains the tep local to
+ * the system
+ */
+struct tep_handle *tracecmd_local_events_system(const char *tracing_dir,
+						const char * const *sys_names)
+{
+	struct tep_handle *tep = NULL;
+
+	tep = tep_alloc();
+	if (!tep)
+		return NULL;
+
+	if (tracecmd_fill_local_events_system(tracing_dir, tep, sys_names, NULL)) {
+		tep_free(tep);
+		tep = NULL;
+	}
+
+	return tep;
+}
+
+/**
+ * tracecmd_local_events - create a pevent from the events on system
+ * @tracing_dir: The directory that contains the events
+ *
+ * Returns a pevent structure that contains the pevents local to
+ * the system
+ */
+struct tep_handle *tracecmd_local_events(const char *tracing_dir)
+{
+	return tracecmd_local_events_system(tracing_dir, NULL);
+}
+
+/**
+ * tracecmd_fill_local_events - Fill a pevent with the events on system
+ * @tracing_dir: The directory that contains the events
+ * @tep: Allocated tep handler which will be filled
+ * @parsing_failures: return number of failures while parsing the event files
+ *
+ * Returns whether the operation succeeded
+ */
+int tracecmd_fill_local_events(const char *tracing_dir,
+			       struct tep_handle *tep, int *parsing_failures)
+{
+	return tracecmd_fill_local_events_system(tracing_dir, tep,
+						 NULL, parsing_failures);
+}
+
 /**
  * tracecmd_local_plugins - returns an array of available tracer plugins
  * @tracing_dir: The directory that contains the tracing directory
-- 
2.23.0

[PATCH v18 02/18] trace-cmd: Add support for negative time offsets in trace.dat file

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

When synchronizing timestamps between different machines, there are cases
when the time offset is negative. This patch changes the way time offset is
written and read from trace.dat file - as signed decimal, instead of hex.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 include/trace-cmd/trace-cmd.h | 2 +-
 lib/trace-cmd/trace-input.c   | 6 +++---
 tracecmd/trace-read.c         | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 9363a26..7f9cb73 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -138,7 +138,7 @@ const char *tracecmd_buffer_instance_name(struct tracecmd_input *handle, int ind
 struct tracecmd_input *tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx);
 int tracecmd_is_buffer_instance(struct tracecmd_input *handle);
 
-void tracecmd_set_ts_offset(struct tracecmd_input *handle, unsigned long long offset);
+void tracecmd_set_ts_offset(struct tracecmd_input *handle, long long offset);
 void tracecmd_set_ts2secs(struct tracecmd_input *handle, unsigned long long hz);
 
 void tracecmd_print_events(struct tracecmd_input *handle, const char *regex);
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 3b187e3..91362f3 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -90,7 +90,7 @@ struct tracecmd_input {
 	bool			read_page;
 	bool			use_pipe;
 	struct cpu_data 	*cpu_data;
-	unsigned long long	ts_offset;
+	long long		ts_offset;
 	double			ts2secs;
 	char *			cpustats;
 	char *			uname;
@@ -2127,7 +2127,7 @@ static int init_cpu(struct tracecmd_input *handle, int cpu)
 }
 
 void tracecmd_set_ts_offset(struct tracecmd_input *handle,
-			    unsigned long long offset)
+			    long long offset)
 {
 	handle->ts_offset = offset;
 }
@@ -2305,7 +2305,7 @@ tracecmd_search_task_map(struct tracecmd_input *handle,
 
 static int handle_options(struct tracecmd_input *handle)
 {
-	unsigned long long offset;
+	long long offset;
 	unsigned short option;
 	unsigned int size;
 	char *cpustats = NULL;
diff --git a/tracecmd/trace-read.c b/tracecmd/trace-read.c
index c0d640d..4ce2e98 100644
--- a/tracecmd/trace-read.c
+++ b/tracecmd/trace-read.c
@@ -58,7 +58,7 @@ static struct list_head handle_list;
 struct input_files {
 	struct list_head	list;
 	const char		*file;
-	unsigned long long	tsoffset;
+	long long		tsoffset;
 	unsigned long long	ts2secs;
 };
 static struct list_head input_files;
@@ -1466,7 +1466,7 @@ void trace_report (int argc, char **argv)
 	struct input_files *inputs;
 	struct handle_list *handles;
 	enum output_type otype;
-	unsigned long long tsoffset = 0;
+	long long tsoffset = 0;
 	unsigned long long ts2secs = 0;
 	unsigned long long ts2sc;
 	int show_stat = 0;
-- 
2.23.0

[PATCH v18 03/18] trace-cmd: Add implementations of htonll() and ntohll()

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

Implementations of htonll() and ntohll() are added as
macros, if they are not already defined.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 include/trace-cmd/trace-msg.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/trace-cmd/trace-msg.h b/include/trace-cmd/trace-msg.h
index aab8a69..654ca43 100644
--- a/include/trace-cmd/trace-msg.h
+++ b/include/trace-cmd/trace-msg.h
@@ -12,4 +12,14 @@
 
 extern unsigned int page_size;
 
+#ifndef htonll
+# if __BYTE_ORDER == __LITTLE_ENDIAN
+#define htonll(x) __bswap_64(x)
+#define ntohll(x) __bswap_64(x)
+#else
+#define htonll(x) (x)
+#define ntohll(x) (x)
+#endif
+#endif
+
 #endif /* _TRACE_MSG_H_ */
-- 
2.23.0

[PATCH v18 04/18] trace-cmd: Add new library APIs for ftrace instances.

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

In order to reuse the code, the functionality related to
ftrace instances is moved from trace-cmd application to
libtracecmd. The following new library APIs are introduced:

library structure, representing a ftrace instance:
	struct tracecmd_instance;

APIs for creating and deleting ftrace instances:
	struct tracecmd_instance *tracecmd_alloc_instance(const char *name);
	void tracecmd_free_instance(struct tracecmd_instance *instance);
	int tracecmd_make_instance(struct tracecmd_instance *instance);
	int tracecmd_remove_instance(struct tracecmd_instance *instance);

APIs for getting and setting ftrace instance parameters:
        char *tracecmd_get_instance_name(struct tracecmd_instance *instance);
        int tracecmd_alloc_instance_clock(struct tracecmd_instance *instance, const char *clock);
        char *tracecmd_get_instance_clock(struct tracecmd_instance *instance);

APIs for reading and writing ftrace files, instance aware:
	char *tracecmd_get_instance_file(struct tracecmd_instance *instance, const char *file);
	char *tracecmd_get_instance_dir(struct tracecmd_instance *instance);
	int tracecmd_write_instance_file(struct tracecmd_instance *instance,
	                                 const char *file, const char *str,
        	                         const char *type);
	int tracecmd_write_file(const char *file, const char *str, const char *type);
	char *tracecmd_read_instance_file(struct tracecmd_instance *instance,
        	                          char *file, int *psize);

API for setting ftrace clock, instance aware:
	int tracecmd_set_clock(struct tracecmd_instance *instance, char **old_clock);

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h           |  24 ++
 lib/trace-cmd/Makefile                  |   1 +
 lib/trace-cmd/include/trace-cmd-local.h |  33 +--
 lib/trace-cmd/trace-instance.c          | 335 +++++++++++++++++++++++
 lib/trace-cmd/trace-util.c              |  71 ++++-
 tracecmd/include/trace-local.h          |   6 +-
 tracecmd/trace-list.c                   |   2 +-
 tracecmd/trace-record.c                 | 343 +++++++-----------------
 tracecmd/trace-show.c                   |   2 +
 tracecmd/trace-stat.c                   |  20 +-
 10 files changed, 544 insertions(+), 293 deletions(-)
 create mode 100644 lib/trace-cmd/trace-instance.c

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 7f9cb73..32182bc 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -356,6 +356,30 @@ int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int *nr_cpus, int *page_size,
 				 unsigned int **ports, bool *use_fifos);
+/* --- ftrace instances --- */
+
+struct tracecmd_instance;
+
+struct tracecmd_instance *tracecmd_alloc_instance(const char *name);
+void tracecmd_free_instance(struct tracecmd_instance *instance);
+int tracecmd_make_instance(struct tracecmd_instance *instance);
+int tracecmd_remove_instance(struct tracecmd_instance *instance);
+char *
+tracecmd_get_instance_file(struct tracecmd_instance *instance, const char *file);
+char *tracecmd_get_instance_dir(struct tracecmd_instance *instance);
+int tracecmd_write_instance_file(struct tracecmd_instance *instance,
+				 const char *file, const char *str,
+				 const char *type);
+
+int tracecmd_write_file(const char *file, const char *str, const char *type);
+char *tracecmd_read_instance_file(struct tracecmd_instance *instance,
+				  char *file, int *psize);
+char *tracecmd_get_instance_name(struct tracecmd_instance *instance);
+int tracecmd_alloc_instance_clock(struct tracecmd_instance *instance,
+				  const char *clock);
+char *tracecmd_get_instance_clock(struct tracecmd_instance *instance);
+int tracecmd_set_clock(struct tracecmd_instance *instance, char **old_clock);
+
 
 /* --- Plugin handling --- */
 extern struct tep_plugin_option trace_ftrace_options[];
diff --git a/lib/trace-cmd/Makefile b/lib/trace-cmd/Makefile
index 3b4b5aa..18c7013 100644
--- a/lib/trace-cmd/Makefile
+++ b/lib/trace-cmd/Makefile
@@ -13,6 +13,7 @@ OBJS += trace-input.o
 OBJS += trace-output.o
 OBJS += trace-recorder.o
 OBJS += trace-util.o
+OBJS += trace-instance.o
 OBJS += trace-filter-hash.o
 OBJS += trace-msg.o
 
diff --git a/lib/trace-cmd/include/trace-cmd-local.h b/lib/trace-cmd/include/trace-cmd-local.h
index 09574db..eef4d39 100644
--- a/lib/trace-cmd/include/trace-cmd-local.h
+++ b/lib/trace-cmd/include/trace-cmd-local.h
@@ -18,36 +18,7 @@
 #define STR(x)	_STR(x)
 #define FILE_VERSION_STRING STR(FILE_VERSION)
 
-static ssize_t __do_write(int fd, const void *data, size_t size)
-{
-	ssize_t tot = 0;
-	ssize_t w;
-
-	do {
-		w = write(fd, data + tot, size - tot);
-		tot += w;
-
-		if (!w)
-			break;
-		if (w < 0)
-			return w;
-	} while (tot != size);
-
-	return tot;
-}
-
-static ssize_t
-__do_write_check(int fd, const void *data, size_t size)
-{
-	ssize_t ret;
-
-	ret = __do_write(fd, data, size);
-	if (ret < 0)
-		return ret;
-	if (ret != size)
-		return -1;
-
-	return 0;
-}
+ssize_t __do_write_check(int fd, const void *data, size_t size);
+void __noreturn die(const char *fmt, ...); /* Can be overriden */
 
 #endif /* _TRACE_CMD_LOCAL_H */
diff --git a/lib/trace-cmd/trace-instance.c b/lib/trace-cmd/trace-instance.c
new file mode 100644
index 0000000..02d4bb3
--- /dev/null
+++ b/lib/trace-cmd/trace-instance.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2019, VMware, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <time.h>
+#include <poll.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+#include "trace-cmd.h"
+#include "trace-cmd-local.h"
+
+struct tracecmd_instance {
+	char	*name;
+	char	*clock;
+};
+
+/**
+ * tracecmd_put_tracing_file - Free tracing file / dir, created by
+ *		tracecmd_get_instance_dir() or tracecmd_get_instance_file()
+ *		APIs.
+ *@name: The name of the tracing file or dir
+ */
+void tracecmd_put_tracing_file(char *name)
+{
+	free(name);
+}
+
+/**
+ * tracecmd_alloc_instance - allocate a new ftrace instance
+ * @name: The name of the instance (instance will point to this)
+ *
+ * Returns a newly allocated instance. Note that @name will not be
+ * copied, and the instance buffer will point to the string itself
+ */
+struct tracecmd_instance *tracecmd_alloc_instance(const char *name)
+{
+	struct tracecmd_instance *instance;
+
+	instance = malloc(sizeof(*instance));
+	if (!instance)
+		return NULL;
+	memset(instance, 0, sizeof(*instance));
+	if (name)
+		instance->name = strdup(name);
+
+	return instance;
+}
+
+/**
+ * tracecmd_free_instance - Free an instance struct, previously allocated by
+ *			    tracecmd_alloc_instance()
+ *@instance: Pointer to the instance to be freed
+ *
+ */
+void tracecmd_free_instance(struct tracecmd_instance *instance)
+{
+	if (!instance)
+		return;
+
+	free(instance->clock);
+	free(instance->name);
+	free(instance);
+}
+
+/**
+ * tracecmd_make_instance - Create a new ftrace instance
+ * @instance: Pointer to the instance to be created
+ *
+ * Returns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_make_instance(struct tracecmd_instance *instance)
+{
+	struct stat st;
+	char *path;
+	int ret;
+
+	path = tracecmd_get_instance_dir(instance);
+	ret = stat(path, &st);
+	if (ret < 0) {
+		ret = mkdir(path, 0777);
+		if (ret < 0)
+			return ret;
+
+	} else
+		ret = 1;
+	tracecmd_put_tracing_file(path);
+	return ret;
+}
+
+/**
+ * tracecmd_remove_instance - Remove a ftrace instance
+ * @instance: Pointer to the instance to be removed
+ *
+ * Returns 0 on successful completion, otherwise -1
+ */
+int tracecmd_remove_instance(struct tracecmd_instance *instance)
+{
+	char *path;
+	int ret;
+
+	path = tracecmd_get_instance_dir(instance);
+	ret = rmdir(path);
+	tracecmd_put_tracing_file(path);
+
+	return ret;
+}
+
+/**
+ * tracecmd_get_instance_file - return the path to a instance file
+ * @instance: buffer instance for the file, can be NULL for the top instance
+ * @file: name of file to return
+ *
+ * Returns the path name of the @file for the given @instance
+ *
+ * Must use tracecmd_put_tracing_file() to free the returned string
+ */
+char *
+tracecmd_get_instance_file(struct tracecmd_instance *instance, const char *file)
+{
+	char *path;
+	char *buf;
+	int ret;
+
+	if (instance && instance->name) {
+		ret = asprintf(&buf, "instances/%s/%s", instance->name, file);
+		if (ret < 0)
+			die("Failed to allocate name for %s/%s", instance->name, file);
+		path = tracecmd_get_tracing_file(buf);
+		free(buf);
+	} else
+		path = tracecmd_get_tracing_file(file);
+
+	return path;
+}
+
+/**
+ * tracecmd_get_instance_file - return the path to a instance file
+ * @instance: buffer instance for the file, can be NULL for the top instance
+ * @file: name of file to return
+ *
+ * Returns the path name of the @file for the given @instance
+ *
+ * Must use tracecmd_put_tracing_file() to free the returned string
+ */
+char *tracecmd_get_instance_dir(struct tracecmd_instance *instance)
+{
+	char *buf;
+	char *path;
+	int ret;
+
+	if (instance->name) {
+		ret = asprintf(&buf, "instances/%s", instance->name);
+		if (ret < 0)
+			die("Failed to allocate for instance %s", instance->name);
+		path = tracecmd_get_tracing_file(buf);
+		free(buf);
+	} else
+		path = tracecmd_find_tracing_dir();
+
+	return path;
+}
+
+/**
+ * tracecmd_write_instance_file - Write in trace file of specific instance
+ * @instance: buffer instance for the file, can be NULL for the top instance
+ * @file: name of the file
+ * @str: Nul terminated string, that will be written in the file
+ * @type: Nul terminated string, describing the current write operation
+ *	  Used for logging purposes
+ *
+ * Returns the number of written bytes, or -1 in case of an error
+ */
+int tracecmd_write_instance_file(struct tracecmd_instance *instance,
+				 const char *file, const char *str,
+				 const char *type)
+{
+	struct stat st;
+	char *path;
+	int ret;
+
+	path = tracecmd_get_instance_file(instance, file);
+	ret = stat(path, &st);
+	if (ret == 0)
+		ret = tracecmd_write_file(path, str, type);
+	tracecmd_put_tracing_file(path);
+
+	return ret;
+}
+
+/**
+ * tracecmd_read_instance_file - Read from a trace file of specific instance
+ * @instance: buffer instance for the file, can be NULL for the top instance
+ * @file: name of the file
+ * @psize: Returns the number of bytes read
+ *
+ * Returns a pointer to a nul terminated string, read from the file, or NULL in
+ * case of an error
+ * The returned string must be freed via free()
+ */
+char *tracecmd_read_instance_file(struct tracecmd_instance *instance,
+				  char *file, int *psize)
+{
+	char buffer[BUFSIZ];
+	char *buf = NULL;
+	int size = 0;
+	char *path;
+	int fd;
+	int r;
+
+	path = tracecmd_get_instance_file(instance, file);
+	fd = open(path, O_RDONLY);
+	tracecmd_put_tracing_file(path);
+	if (fd < 0) {
+		warning("File %s not found", file);
+		return NULL;
+	}
+
+	do {
+		r = read(fd, buffer, BUFSIZ);
+		if (r <= 0)
+			continue;
+		buf = realloc(buf, size + r + 1);
+		if (!buf) {
+			warning("Failed to allocate %d bytes instance file buffer",
+				size + r + 1);
+			return NULL;
+		}
+		memcpy(buf + size, buffer, r);
+		size += r;
+	} while (r);
+
+	buf[size] = '\0';
+	if (psize)
+		*psize = size;
+	return buf;
+}
+
+/**
+ * tracecmd_get_instance_name - Return the name of the instance
+ * @instance: Pointer to ftrace instance
+ *
+ * Returns nul terminated string, the name of the instance
+ */
+char *tracecmd_get_instance_name(struct tracecmd_instance *instance)
+{
+	if (instance)
+		return instance->name;
+
+	return NULL;
+}
+
+/**
+ * tracecmd_alloc_instance_clock - Allocate new clock for an instance
+ * @instance: Pointer to ftrace instance
+ * @clock: nul terminated string, the new clock
+ *
+ * Returns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_alloc_instance_clock(struct tracecmd_instance *instance,
+				  const char *clock)
+{
+	if (!instance || !clock)
+		return -1;
+
+	if (instance->clock)
+		free (instance->clock);
+
+	instance->clock = strdup(clock);
+	if (!instance->clock)
+		return -1;
+
+	return 0;
+}
+
+/**
+ * tracecmd_get_instance_clock - Get clock of an instance
+ * @instance: Pointer to ftrace instance
+ *
+ * Returns nul terminated string, the clock of the instance
+ */
+char *tracecmd_get_instance_clock(struct tracecmd_instance *instance)
+{
+	if (instance)
+		return instance->clock;
+
+	return NULL;
+}
+
+/**
+ * tracecmd_set_clock - Set the clock of ftrace event's timestamps, per instance
+ * @instance: Pointer to ftrace instance, containing the desired clock
+ * @old_clock: Optional, return the newly allocated string with the old clock
+ *
+ * Returns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_set_clock(struct tracecmd_instance *instance, char **old_clock)
+{
+	char *content;
+	char *str;
+	int ret;
+
+	if (!instance->clock)
+		return -1;
+
+	/* The current clock is in brackets, reset it when we are done */
+	content = tracecmd_read_instance_file(instance, "trace_clock", NULL);
+
+	/* check if first clock is set */
+	if (*content == '[')
+		str = strtok(content+1, "]");
+	else {
+		str = strtok(content, "[");
+		if (!str)
+			die("Can not find clock in trace_clock");
+		str = strtok(NULL, "]");
+	}
+	if (old_clock)
+		*old_clock = strdup(str);
+
+	free(content);
+	ret = tracecmd_write_instance_file(instance,
+					   "trace_clock", instance->clock,
+					   "clock");
+	if (ret > 0)
+		return 0;
+
+	return -1;
+}
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index e93225f..582709f 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -918,11 +918,6 @@ char *tracecmd_get_tracing_file(const char *name)
 	return file;
 }
 
-void tracecmd_put_tracing_file(char *name)
-{
-	free(name);
-}
-
 void __noreturn __vdie(const char *fmt, va_list ap)
 {
 	int ret = errno;
@@ -967,6 +962,38 @@ void __weak *malloc_or_die(unsigned int size)
 	return data;
 }
 
+
+static ssize_t __do_write(int fd, const void *data, size_t size)
+{
+	ssize_t tot = 0;
+	ssize_t w;
+
+	do {
+		w = write(fd, data + tot, size - tot);
+		tot += w;
+
+		if (!w)
+			break;
+		if (w < 0)
+			return w;
+	} while (tot != size);
+
+	return tot;
+}
+
+ssize_t
+__do_write_check(int fd, const void *data, size_t size)
+{
+	ssize_t ret;
+
+	ret = __do_write(fd, data, size);
+	if (ret < 0)
+		return ret;
+	if (ret != size)
+		return -1;
+
+	return 0;
+}
 #define LOG_BUF_SIZE 1024
 static void __plog(const char *prefix, const char *fmt, va_list ap, FILE *fp)
 {
@@ -1084,3 +1111,37 @@ int tracecmd_stack_tracer_status(int *status)
 	*status = num;
 	return 1; /* full success */
 }
+
+/*
+ * tracecmd_write_file - Write in trace file
+ * @file: Full name of the trace file.
+ * @str: Null terminated string, that will be written in the file.
+ * @type: Null terminated string, describing the current write operation.
+ *	  Used for logging purposes.
+ *
+ * Returns the number of written bytes, or -1 in case of an error
+ */
+int tracecmd_write_file(const char *file, const char *str, const char *type)
+{
+	char buf[BUFSIZ];
+	int ret;
+	int fd;
+
+	fd = open(file, O_WRONLY | O_TRUNC);
+	if (fd < 0)
+		die("opening to '%s'", file);
+	ret = write(fd, str, strlen(str));
+	close(fd);
+	if (ret < 0 && type) {
+		/* write failed */
+		fd = open(file, O_RDONLY);
+		if (fd < 0)
+			die("writing to '%s'", file);
+		/* the filter has the error */
+		while ((ret = read(fd, buf, BUFSIZ)) > 0)
+			fprintf(stderr, "%.*s", ret, buf);
+		die("Failed %s of %s\n", type, file);
+		close(fd);
+	}
+	return ret;
+}
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index fedc0b7..3a05e9c 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -181,7 +181,7 @@ struct pid_addr_maps {
 
 struct buffer_instance {
 	struct buffer_instance	*next;
-	const char		*name;
+	struct tracecmd_instance	*ftrace;
 	char			*cpumask;
 	struct event_list	*events;
 	struct event_list	**event_next;
@@ -195,7 +195,6 @@ struct buffer_instance {
 	struct func_list	*filter_funcs;
 	struct func_list	*notrace_funcs;
 
-	const char		*clock;
 	unsigned int		*client_ports;
 
 	struct trace_seq	*s_save;
@@ -225,6 +224,8 @@ struct buffer_instance {
 	bool			use_fifos;
 };
 
+void init_top_instance(void);
+
 extern struct buffer_instance top_instance;
 extern struct buffer_instance *buffer_instances;
 extern struct buffer_instance *first_instance;
@@ -238,7 +239,6 @@ extern struct buffer_instance *first_instance;
 
 struct buffer_instance *create_instance(const char *name);
 void add_instance(struct buffer_instance *instance, int cpu_count);
-char *get_instance_file(struct buffer_instance *instance, const char *file);
 void update_first_instance(struct buffer_instance *instance, int topt);
 
 void show_instance_file(struct buffer_instance *instance, const char *name);
diff --git a/tracecmd/trace-list.c b/tracecmd/trace-list.c
index 65099a5..e0782ed 100644
--- a/tracecmd/trace-list.c
+++ b/tracecmd/trace-list.c
@@ -33,7 +33,7 @@ void show_instance_file(struct buffer_instance *instance, const char *name)
 {
 	char *path;
 
-	path = get_instance_file(instance, name);
+	path = tracecmd_get_instance_file(instance->ftrace, name);
 	dump_file_content(path);
 	tracecmd_put_tracing_file(path);
 }
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 80b2234..3f4f55f 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -173,7 +173,7 @@ static struct reset_file *reset_files;
 /* Triggers need to be cleared in a special way */
 static struct reset_file *reset_triggers;
 
-struct buffer_instance top_instance = { .flags = BUFFER_FL_KEEP };
+struct buffer_instance top_instance;
 struct buffer_instance *buffer_instances;
 struct buffer_instance *first_instance;
 
@@ -191,7 +191,7 @@ static inline int no_top_instance(void)
 	return first_instance != &top_instance;
 }
 
-static void init_instance(struct buffer_instance *instance)
+void tracecmd_init_instance(struct buffer_instance *instance)
 {
 	instance->event_next = &instance->events;
 }
@@ -318,7 +318,7 @@ static void reset_save_file_cond(const char *file, int prio,
  */
 void add_instance(struct buffer_instance *instance, int cpu_count)
 {
-	init_instance(instance);
+	tracecmd_init_instance(instance);
 	instance->next = buffer_instances;
 	if (first_instance == buffer_instances)
 		first_instance = instance;
@@ -371,7 +371,12 @@ struct buffer_instance *create_instance(const char *name)
 	if (!instance)
 		return NULL;
 	memset(instance, 0, sizeof(*instance));
-	instance->name = name;
+
+	instance->ftrace = tracecmd_alloc_instance(name);
+	if (!instance->ftrace) {
+		free(instance);
+		return NULL;
+	}
 
 	return instance;
 }
@@ -471,7 +476,7 @@ void tracecmd_stat_cpu_instance(struct buffer_instance *instance,
 		return;
 	snprintf(file, 40, "per_cpu/cpu%d/stats", cpu);
 
-	path = get_instance_file(instance, file);
+	path = tracecmd_get_instance_file(instance->ftrace, file);
 	free(file);
 	fd = open(path, O_RDONLY);
 	tracecmd_put_tracing_file(path);
@@ -505,12 +510,12 @@ static void add_event(struct buffer_instance *instance, struct event_list *event
 static void reset_event_list(struct buffer_instance *instance)
 {
 	instance->events = NULL;
-	init_instance(instance);
+	tracecmd_init_instance(instance);
 }
 
 static char *get_temp_file(struct buffer_instance *instance, int cpu)
 {
-	const char *name = instance->name;
+	const char *name = tracecmd_get_instance_name(instance->ftrace);
 	char *file = NULL;
 	int size;
 
@@ -557,7 +562,7 @@ static void put_temp_file(char *file)
 
 static void delete_temp_file(struct buffer_instance *instance, int cpu)
 {
-	const char *name = instance->name;
+	const char *name = tracecmd_get_instance_name(instance->ftrace);
 	char file[PATH_MAX];
 
 	if (name)
@@ -783,96 +788,6 @@ static int set_ftrace(int set, int use_proc)
 	return 0;
 }
 
-/**
- * get_instance_file - return the path to a instance file.
- * @instance: buffer instance for the file
- * @file: name of file to return
- *
- * Returns the path name of the @file for the given @instance.
- *
- * Must use tracecmd_put_tracing_file() to free the returned string.
- */
-char *
-get_instance_file(struct buffer_instance *instance, const char *file)
-{
-	char *buf;
-	char *path;
-	int ret;
-
-	if (instance->name) {
-		ret = asprintf(&buf, "instances/%s/%s", instance->name, file);
-		if (ret < 0)
-			die("Failed to allocate name for %s/%s", instance->name, file);
-		path = tracecmd_get_tracing_file(buf);
-		free(buf);
-	} else
-		path = tracecmd_get_tracing_file(file);
-
-	return path;
-}
-
-static char *
-get_instance_dir(struct buffer_instance *instance)
-{
-	char *buf;
-	char *path;
-	int ret;
-
-	/* only works for instances */
-	if (!instance->name)
-		return NULL;
-
-	ret = asprintf(&buf, "instances/%s", instance->name);
-	if (ret < 0)
-		die("Failed to allocate for instance %s", instance->name);
-	path = tracecmd_get_tracing_file(buf);
-	free(buf);
-
-	return path;
-}
-
-static int write_file(const char *file, const char *str, const char *type)
-{
-	char buf[BUFSIZ];
-	int fd;
-	int ret;
-
-	fd = open(file, O_WRONLY | O_TRUNC);
-	if (fd < 0)
-		die("opening to '%s'", file);
-	ret = write(fd, str, strlen(str));
-	close(fd);
-	if (ret < 0 && type) {
-		/* write failed */
-		fd = open(file, O_RDONLY);
-		if (fd < 0)
-			die("writing to '%s'", file);
-		/* the filter has the error */
-		while ((ret = read(fd, buf, BUFSIZ)) > 0)
-			fprintf(stderr, "%.*s", ret, buf);
-		die("Failed %s of %s\n", type, file);
-		close(fd);
-	}
-	return ret;
-}
-
-static int
-write_instance_file(struct buffer_instance *instance,
-		    const char *file, const char *str, const char *type)
-{
-	struct stat st;
-	char *path;
-	int ret;
-
-	path = get_instance_file(instance, file);
-	ret = stat(path, &st);
-	if (ret == 0)
-		ret = write_file(path, str, type);
-	tracecmd_put_tracing_file(path);
-
-	return ret;
-}
-
 static void __clear_trace(struct buffer_instance *instance)
 {
 	FILE *fp;
@@ -882,7 +797,7 @@ static void __clear_trace(struct buffer_instance *instance)
 		return;
 
 	/* reset the trace */
-	path = get_instance_file(instance, "trace");
+	path = tracecmd_get_instance_file(instance->ftrace, "trace");
 	fp = fopen(path, "w");
 	if (!fp)
 		die("writing to '%s'", path);
@@ -916,8 +831,8 @@ static void clear_trace(void)
 
 static void reset_max_latency(struct buffer_instance *instance)
 {
-	 write_instance_file(instance,
-			     "tracing_max_latency", "0", "max_latency");
+	tracecmd_write_instance_file(instance->ftrace,
+				     "tracing_max_latency", "0", "max_latency");
 }
 
 static void add_filter_pid(int pid, int exclude)
@@ -1363,7 +1278,8 @@ static void add_event_pid(const char *buf)
 	struct buffer_instance *instance;
 
 	for_all_instances(instance)
-		write_instance_file(instance, "set_event_pid", buf, "event_pid");
+		tracecmd_write_instance_file(instance->ftrace,
+					     "set_event_pid", buf, "event_pid");
 }
 
 static void add_new_filter_pid(int pid)
@@ -1592,7 +1508,7 @@ set_plugin_instance(struct buffer_instance *instance, const char *name)
 	if (is_guest(instance))
 		return;
 
-	path = get_instance_file(instance, "current_tracer");
+	path = tracecmd_get_instance_file(instance->ftrace, "current_tracer");
 	fp = fopen(path, "w");
 	if (!fp) {
 		/*
@@ -1616,7 +1532,7 @@ set_plugin_instance(struct buffer_instance *instance, const char *name)
 
 	/* Make sure func_stack_trace option is disabled */
 	/* First try instance file, then top level */
-	path = get_instance_file(instance, "options/func_stack_trace");
+	path = tracecmd_get_instance_file(instance->ftrace, "options/func_stack_trace");
 	fp = fopen(path, "w");
 	if (!fp) {
 		tracecmd_put_tracing_file(path);
@@ -1677,8 +1593,6 @@ static int set_option(const char *option)
 	return 0;
 }
 
-static char *read_instance_file(struct buffer_instance *instance, char *file, int *psize);
-
 static void disable_func_stack_trace_instance(struct buffer_instance *instance)
 {
 	struct stat st;
@@ -1691,13 +1605,13 @@ static void disable_func_stack_trace_instance(struct buffer_instance *instance)
 	if (is_guest(instance))
 		return;
 
-	path = get_instance_file(instance, "current_tracer");
+	path = tracecmd_get_instance_file(instance->ftrace, "current_tracer");
 	ret = stat(path, &st);
 	tracecmd_put_tracing_file(path);
 	if (ret < 0)
 		return;
 
-	content = read_instance_file(instance, "current_tracer", &size);
+	content = tracecmd_read_instance_file(instance->ftrace, "current_tracer", &size);
 	cond = strstrip(content);
 	if (memcmp(cond, "function", size - (cond - content)) !=0)
 		goto out;
@@ -1850,7 +1764,7 @@ static int trace_check_file_exists(struct buffer_instance *instance, char *file)
 	char *path;
 	int ret;
 
-	path = get_instance_file(instance, file);
+	path = tracecmd_get_instance_file(instance->ftrace, file);
 	ret = stat(path, &st);
 	tracecmd_put_tracing_file(path);
 
@@ -1929,7 +1843,7 @@ reset_events_instance(struct buffer_instance *instance)
 	}
 
 	c = '0';
-	path = get_instance_file(instance, "events/enable");
+	path = tracecmd_get_instance_file(instance->ftrace, "events/enable");
 	fd = open(path, O_WRONLY);
 	if (fd < 0)
 		die("opening to '%s'", path);
@@ -1937,7 +1851,7 @@ reset_events_instance(struct buffer_instance *instance)
 	close(fd);
 	tracecmd_put_tracing_file(path);
 
-	path = get_instance_file(instance, "events/*/filter");
+	path = tracecmd_get_instance_file(instance->ftrace, "events/*/filter");
 	globbuf.gl_offs = 0;
 	ret = glob(path, 0, NULL, &globbuf);
 	tracecmd_put_tracing_file(path);
@@ -2009,7 +1923,7 @@ static int find_trigger(const char *file, char *buf, int size, int fields)
 
 static void write_filter(const char *file, const char *filter)
 {
-	write_file(file, filter, "filter");
+	tracecmd_write_file(file, filter, "filter");
 }
 
 static void clear_filter(const char *file)
@@ -2019,12 +1933,12 @@ static void clear_filter(const char *file)
 
 static void write_trigger(const char *file, const char *trigger)
 {
-	write_file(file, trigger, "trigger");
+	tracecmd_write_file(file, trigger, "trigger");
 }
 
 static void write_func_filter(const char *file, const char *trigger)
 {
-	write_file(file, trigger, "function filter");
+	tracecmd_write_file(file, trigger, "function filter");
 }
 
 static void clear_trigger(const char *file)
@@ -2117,7 +2031,7 @@ static void update_reset_files(void)
 		reset_files = reset->next;
 
 		if (!keep)
-			write_file(reset->path, reset->reset, "reset");
+			tracecmd_write_file(reset->path, reset->reset, "reset");
 		free(reset->path);
 		free(reset->reset);
 		free(reset);
@@ -2198,7 +2112,7 @@ static int open_instance_fd(struct buffer_instance *instance,
 	int fd;
 	char *path;
 
-	path = get_instance_file(instance, file);
+	path = tracecmd_get_instance_file(instance->ftrace, file);
 	fd = open(path, flags);
 	if (fd < 0) {
 		/* instances may not be created yet */
@@ -2227,7 +2141,7 @@ static int open_tracing_on(struct buffer_instance *instance)
 	return fd;
 }
 
-static void write_tracing_on(struct buffer_instance *instance, int on)
+void write_tracing_on(struct buffer_instance *instance, int on)
 {
 	int ret;
 	int fd;
@@ -2507,7 +2421,7 @@ static void set_mask(struct buffer_instance *instance)
 	if (!instance->cpumask)
 		return;
 
-	path = get_instance_file(instance, "tracing_cpumask");
+	path = tracecmd_get_instance_file(instance->ftrace, "tracing_cpumask");
 	if (!path)
 		die("could not allocate path");
 	reset_save_file(path, RESET_DEFAULT_PRIO);
@@ -2555,39 +2469,6 @@ void tracecmd_enable_events(void)
 	enable_events(first_instance);
 }
 
-static void set_clock(struct buffer_instance *instance)
-{
-	char *path;
-	char *content;
-	char *str;
-
-	if (is_guest(instance))
-		return;
-
-	if (!instance->clock)
-		return;
-
-	/* The current clock is in brackets, reset it when we are done */
-	content = read_instance_file(instance, "trace_clock", NULL);
-
-	/* check if first clock is set */
-	if (*content == '[')
-		str = strtok(content+1, "]");
-	else {
-		str = strtok(content, "[");
-		if (!str)
-			die("Can not find clock in trace_clock");
-		str = strtok(NULL, "]");
-	}
-	path = get_instance_file(instance, "trace_clock");
-	add_reset_file(path, str, RESET_DEFAULT_PRIO);
-
-	free(content);
-	tracecmd_put_tracing_file(path);
-
-	write_instance_file(instance, "trace_clock", instance->clock, "clock");
-}
-
 static void set_max_graph_depth(struct buffer_instance *instance, char *max_graph_depth)
 {
 	char *path;
@@ -2596,16 +2477,16 @@ static void set_max_graph_depth(struct buffer_instance *instance, char *max_grap
 	if (is_guest(instance))
 		return;
 
-	path = get_instance_file(instance, "max_graph_depth");
+	path = tracecmd_get_instance_file(instance->ftrace, "max_graph_depth");
 	reset_save_file(path, RESET_DEFAULT_PRIO);
 	tracecmd_put_tracing_file(path);
-	ret = write_instance_file(instance, "max_graph_depth", max_graph_depth,
-				  NULL);
+	ret = tracecmd_write_instance_file(instance->ftrace,
+					   "max_graph_depth", max_graph_depth,
+					   NULL);
 	if (ret < 0)
 		die("could not write to max_graph_depth");
 }
 
-
 /**
  * create_event - create and event descriptor
  * @instance: instance to use
@@ -2717,7 +2598,7 @@ static int expand_event_files(struct buffer_instance *instance,
 	if (ret < 0)
 		die("Failed to allocate event filter path for %s", file);
 
-	path = get_instance_file(instance, p);
+	path = tracecmd_get_instance_file(instance->ftrace, p);
 
 	globbuf.gl_offs = 0;
 	ret = glob(path, 0, NULL, &globbuf);
@@ -3179,10 +3060,7 @@ create_recorder_instance_pipe(struct buffer_instance *instance,
 	unsigned flags = recorder_flags | TRACECMD_RECORD_BLOCK;
 	char *path;
 
-	if (instance->name)
-		path = get_instance_dir(instance);
-	else
-		path = tracecmd_find_tracing_dir();
+	path = tracecmd_get_instance_dir(instance->ftrace);
 
 	if (!path)
 		die("malloc");
@@ -3192,7 +3070,7 @@ create_recorder_instance_pipe(struct buffer_instance *instance,
 
 	recorder = tracecmd_create_buffer_recorder_fd(brass[1], cpu, flags, path);
 
-	if (instance->name)
+	if (tracecmd_get_instance_name(instance->ftrace))
 		tracecmd_put_tracing_file(path);
 
 	return recorder;
@@ -3227,10 +3105,10 @@ create_recorder_instance(struct buffer_instance *instance, const char *file, int
 	if (brass)
 		return create_recorder_instance_pipe(instance, cpu, brass);
 
-	if (!instance->name)
+	if (!tracecmd_get_instance_name(instance->ftrace))
 		return tracecmd_create_recorder_maxkb(file, cpu, recorder_flags, max_kb);
 
-	path = get_instance_dir(instance);
+	path = tracecmd_get_instance_dir(instance->ftrace);
 
 	record = tracecmd_create_buffer_recorder_maxkb(file, cpu, recorder_flags,
 						       path, max_kb);
@@ -3284,8 +3162,8 @@ static int create_recorder(struct buffer_instance *instance, int cpu,
 		}
 		if (fd < 0)
 			die("Failed connecting to client");
-		if (instance->name && !is_agent(instance))
-			path = get_instance_dir(instance);
+		if (tracecmd_get_instance_name(instance->ftrace) && !is_agent(instance))
+			path = tracecmd_get_instance_dir(instance->ftrace);
 		else
 			path = tracecmd_find_tracing_dir();
 		recorder = tracecmd_create_buffer_recorder_fd(fd, cpu, flags, path);
@@ -3598,7 +3476,8 @@ static void connect_to_agent(struct buffer_instance *instance)
 	bool use_fifos = false;
 
 	if (!no_fifos) {
-		nr_fifos = open_guest_fifos(instance->name, &fds);
+		nr_fifos = open_guest_fifos(tracecmd_get_instance_name(instance->ftrace),
+					    &fds);
 		use_fifos = nr_fifos > 0;
 	}
 
@@ -3625,7 +3504,8 @@ static void connect_to_agent(struct buffer_instance *instance)
 		if (nr_cpus != nr_fifos) {
 			warning("number of FIFOs (%d) for guest %s differs "
 				"from number of virtual CPUs (%d)",
-				nr_fifos, instance->name, nr_cpus);
+				nr_fifos, tracecmd_get_instance_name(instance->ftrace),
+				nr_cpus);
 			nr_cpus = nr_cpus < nr_fifos ? nr_cpus : nr_fifos;
 		}
 		free(ports);
@@ -3651,7 +3531,7 @@ static void setup_guest(struct buffer_instance *instance)
 	int fd;
 
 	/* Create a place to store the guest meta data */
-	file = get_guest_file(output_file, instance->name);
+	file = get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
 	if (!file)
 		die("Failed to allocate memory");
 
@@ -3827,7 +3707,7 @@ add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance
 	int i;
 
 	trace_seq_init(&s);
-	trace_seq_printf(&s, "\nBuffer: %s\n\n", instance->name);
+	trace_seq_printf(&s, "\nBuffer: %s\n\n", tracecmd_get_instance_name(instance->ftrace));
 	tracecmd_add_option(handle, TRACECMD_OPTION_CPUSTAT,
 			    s.len+1, s.buffer);
 	trace_seq_destroy(&s);
@@ -3893,7 +3773,7 @@ static void print_stat(struct buffer_instance *instance)
 		return;
 
 	if (!is_top_instance(instance))
-		printf("\nBuffer: %s\n\n", instance->name);
+		printf("\nBuffer: %s\n\n", tracecmd_get_instance_name(instance->ftrace));
 
 	for (cpu = 0; cpu < instance->cpu_count; cpu++)
 		trace_seq_do_printf(&instance->s_print[cpu]);
@@ -3933,7 +3813,7 @@ static void write_guest_file(struct buffer_instance *instance)
 	char **temp_files;
 	int i, fd;
 
-	file = get_guest_file(output_file, instance->name);
+	file = get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
 	if (!file)
 		die("Failed to allocate memory");
 
@@ -4049,7 +3929,7 @@ static void record_data(struct common_record_context *ctx)
 					continue;
 
 				buffer_options[i++] = tracecmd_add_buffer_option(handle,
-										 instance->name,
+										 tracecmd_get_instance_name(instance->ftrace),
 										 cpus);
 				add_buffer_stat(handle, instance);
 			}
@@ -4096,7 +3976,7 @@ static int write_func_file(struct buffer_instance *instance,
 	if (!*list)
 		return 0;
 
-	path = get_instance_file(instance, file);
+	path = tracecmd_get_instance_file(instance->ftrace, file);
 
 	fd = open(path, O_WRONLY | O_TRUNC);
 	if (fd < 0)
@@ -4140,7 +4020,7 @@ static int functions_filtered(struct buffer_instance *instance)
 	char *path;
 	int fd;
 
-	path = get_instance_file(instance, "set_ftrace_filter");
+	path = tracecmd_get_instance_file(instance->ftrace, "set_ftrace_filter");
 	fd = open(path, O_RDONLY);
 	tracecmd_put_tracing_file(path);
 	if (fd < 0) {
@@ -4148,7 +4028,7 @@ static int functions_filtered(struct buffer_instance *instance)
 			warning("Can not set set_ftrace_filter");
 		else
 			warning("Can not set set_ftrace_filter for %s",
-				instance->name);
+				tracecmd_get_instance_name(instance->ftrace));
 		return 0;
 	}
 
@@ -4308,45 +4188,10 @@ static unsigned long long find_time_stamp(struct tep_handle *pevent)
 	return ts;
 }
 
-static char *read_instance_file(struct buffer_instance *instance, char *file, int *psize)
-{
-	char buffer[BUFSIZ];
-	char *path;
-	char *buf;
-	int size = 0;
-	int fd;
-	int r;
-
-	path = get_instance_file(instance, file);
-	fd = open(path, O_RDONLY);
-	tracecmd_put_tracing_file(path);
-	if (fd < 0) {
-		warning("%s not found, --date ignored", file);
-		return NULL;
-	}
-	do {
-		r = read(fd, buffer, BUFSIZ);
-		if (r <= 0)
-			continue;
-		if (size)
-			buf = realloc(buf, size+r+1);
-		else
-			buf = malloc(r+1);
-		if (!buf)
-			die("Failed to allocate instance file buffer");
-		memcpy(buf+size, buffer, r);
-		size += r;
-	} while (r);
-
-	buf[size] = '\0';
-	if (psize)
-		*psize = size;
-	return buf;
-}
 
 static char *read_file(char *file, int *psize)
 {
-	return read_instance_file(&top_instance, file, psize);
+	return tracecmd_read_instance_file(top_instance.ftrace, file, psize);
 }
 
 /*
@@ -4479,7 +4324,7 @@ static void set_buffer_size_instance(struct buffer_instance *instance)
 
 	snprintf(buf, BUFSIZ, "%d", buffer_size);
 
-	path = get_instance_file(instance, "buffer_size_kb");
+	path = tracecmd_get_instance_file(instance->ftrace, "buffer_size_kb");
 	fd = open(path, O_WRONLY);
 	if (fd < 0) {
 		warning("can't open %s", path);
@@ -4540,7 +4385,7 @@ static void clear_instance_triggers(struct buffer_instance *instance)
 	enum event_iter_type type;
 	enum event_process processed = PROCESSED_NONE;
 
-	path = get_instance_file(instance, "events");
+	path = tracecmd_get_instance_file(instance->ftrace, "events");
 	if (!path)
 		die("malloc");
 
@@ -4601,7 +4446,7 @@ static void clear_instance_filters(struct buffer_instance *instance)
 	enum event_iter_type type;
 	enum event_process processed = PROCESSED_NONE;
 
-	path = get_instance_file(instance, "events");
+	path = tracecmd_get_instance_file(instance->ftrace, "events");
 	if (!path)
 		die("malloc");
 
@@ -4637,7 +4482,8 @@ static void reset_clock(void)
 	struct buffer_instance *instance;
 
 	for_all_instances(instance)
-		write_instance_file(instance, "trace_clock", "local", "clock");
+		tracecmd_write_instance_file(instance->ftrace,
+					    "trace_clock", "local", "clock");
 }
 
 static void reset_cpu_mask(void)
@@ -4656,7 +4502,8 @@ static void reset_cpu_mask(void)
 		strcat(buf, ",ffffffff");
 
 	for_all_instances(instance)
-		write_instance_file(instance, "tracing_cpumask", buf, "cpumask");
+		tracecmd_write_instance_file(instance->ftrace,
+					     "tracing_cpumask", buf, "cpumask");
 }
 
 static void reset_event_pid(void)
@@ -4685,7 +4532,7 @@ static void clear_func_filters(void)
 
 	for_all_instances(instance) {
 		for (i = 0; files[i]; i++) {
-			path = get_instance_file(instance, files[i]);
+			path = tracecmd_get_instance_file(instance->ftrace, files[i]);
 			clear_func_filter(path);
 			tracecmd_put_tracing_file(path);
 		}
@@ -4695,32 +4542,20 @@ static void clear_func_filters(void)
 static void make_instances(void)
 {
 	struct buffer_instance *instance;
-	struct stat st;
-	char *path;
-	int ret;
 
 	for_each_instance(instance) {
 		if (is_guest(instance))
 			continue;
-
-		path = get_instance_dir(instance);
-		ret = stat(path, &st);
-		if (ret < 0) {
-			ret = mkdir(path, 0777);
-			if (ret < 0)
-				die("mkdir %s", path);
-		} else
+		if (tracecmd_make_instance(instance->ftrace) > 0) {
 			/* Don't delete instances that already exist */
 			instance->flags |= BUFFER_FL_KEEP;
-		tracecmd_put_tracing_file(path);
+		}
 	}
 }
 
 void tracecmd_remove_instances(void)
 {
 	struct buffer_instance *instance;
-	char *path;
-	int ret;
 
 	for_each_instance(instance) {
 		/* Only delete what we created */
@@ -4730,11 +4565,7 @@ void tracecmd_remove_instances(void)
 			close(instance->tracing_on_fd);
 			instance->tracing_on_fd = 0;
 		}
-		path = get_instance_dir(instance);
-		ret = rmdir(path);
-		if (ret < 0)
-			die("rmdir %s", path);
-		tracecmd_put_tracing_file(path);
+		tracecmd_remove_instance(instance->ftrace);
 	}
 }
 
@@ -5028,7 +4859,7 @@ static int test_stacktrace_trigger(struct buffer_instance *instance)
 	int ret = 0;
 	int fd;
 
-	path = get_instance_file(instance, "events/sched/sched_switch/trigger");
+	path = tracecmd_get_instance_file(instance->ftrace, "events/sched/sched_switch/trigger");
 
 	clear_trigger(path);
 
@@ -5210,6 +5041,15 @@ void update_first_instance(struct buffer_instance *instance, int topt)
 		first_instance = buffer_instances;
 }
 
+void init_top_instance(void)
+{
+	if (!top_instance.ftrace)
+		top_instance.ftrace = tracecmd_alloc_instance(NULL);
+	top_instance.cpu_count = count_cpus();
+	top_instance.flags = BUFFER_FL_KEEP;
+	tracecmd_init_instance(&top_instance);
+}
+
 enum {
 	OPT_user		= 243,
 	OPT_procmap		= 244,
@@ -5234,7 +5074,7 @@ void trace_stop(int argc, char **argv)
 	int topt = 0;
 	struct buffer_instance *instance = &top_instance;
 
-	init_instance(instance);
+	init_top_instance();
 
 	for (;;) {
 		int c;
@@ -5275,7 +5115,7 @@ void trace_restart(int argc, char **argv)
 	int topt = 0;
 	struct buffer_instance *instance = &top_instance;
 
-	init_instance(instance);
+	init_top_instance();
 
 	for (;;) {
 		int c;
@@ -5317,7 +5157,7 @@ void trace_reset(int argc, char **argv)
 	int topt = 0;
 	struct buffer_instance *instance = &top_instance;
 
-	init_instance(instance);
+	init_top_instance();
 
 	/* if last arg is -a, then -b and -d apply to all instances */
 	int last_specified_all = 0;
@@ -5402,9 +5242,8 @@ static void init_common_record_context(struct common_record_context *ctx,
 	memset(ctx, 0, sizeof(*ctx));
 	ctx->instance = &top_instance;
 	ctx->curr_cmd = curr_cmd;
-	init_instance(ctx->instance);
 	local_cpu_count = count_cpus();
-	ctx->instance->cpu_count = local_cpu_count;
+	init_top_instance();
 }
 
 #define IS_EXTRACT(ctx) ((ctx)->curr_cmd == CMD_extract)
@@ -5642,7 +5481,7 @@ static void parse_record_options(int argc,
 			}
 			break;
 		case 'C':
-			ctx->instance->clock = optarg;
+			tracecmd_alloc_instance_clock(ctx->instance->ftrace, optarg);
 			break;
 		case 'v':
 			neg_event = 1;
@@ -5964,6 +5803,23 @@ static bool has_local_instances(void)
 	return false;
 }
 
+static void set_clock(struct buffer_instance *instance)
+{
+	char *old_clock = NULL;
+	char *path;
+
+	if (is_guest(instance))
+		return;
+
+	tracecmd_set_clock(instance->ftrace, &old_clock);
+	if (old_clock) {
+		path = tracecmd_get_instance_file(instance->ftrace, "trace_clock");
+		if (path)
+			add_reset_file(path, old_clock, RESET_DEFAULT_PRIO);
+		free(old_clock);
+		tracecmd_put_tracing_file(path);
+	}
+}
 /*
  * This function contains common code for the following commands:
  * record, start, stream, profile.
@@ -6015,7 +5871,6 @@ static void record_trace(int argc, char **argv,
 
 	for_all_instances(instance)
 		set_clock(instance);
-
 	/* Record records the date first */
 	if (ctx->date &&
 	    ((IS_RECORD(ctx) && has_local_instances()) || IS_RECORD_AGENT(ctx)))
diff --git a/tracecmd/trace-show.c b/tracecmd/trace-show.c
index 96bfe77..ca0f4cf 100644
--- a/tracecmd/trace-show.c
+++ b/tracecmd/trace-show.c
@@ -51,6 +51,8 @@ void trace_show(int argc, char **argv)
 		{NULL, 0, NULL, 0}
 	};
 
+	init_top_instance();
+
 	while ((c = getopt_long(argc-1, argv+1, "B:c:fsp",
 				long_options, &option_index)) >= 0) {
 		switch (c) {
diff --git a/tracecmd/trace-stat.c b/tracecmd/trace-stat.c
index 538f4ad..5cc9d28 100644
--- a/tracecmd/trace-stat.c
+++ b/tracecmd/trace-stat.c
@@ -30,7 +30,7 @@ static int get_instance_file_fd(struct buffer_instance *instance,
 	char *path;
 	int fd;
 
-	path = get_instance_file(instance, file);
+	path = tracecmd_get_instance_file(instance->ftrace, file);
 	fd = open(path, O_RDONLY);
 	tracecmd_put_tracing_file(path);
 
@@ -347,7 +347,7 @@ static void report_events(struct buffer_instance *instance)
 
 	free(str);
 
-	path = get_instance_file(instance, "events");
+	path = tracecmd_get_instance_file(instance->ftrace, "events");
 	if (!path)
 		die("malloc");
 
@@ -436,7 +436,7 @@ static void report_event_filters(struct buffer_instance *instance)
 	enum event_iter_type type;
 	enum event_process processed = PROCESSED_NONE;
 
-	path = get_instance_file(instance, "events");
+	path = tracecmd_get_instance_file(instance->ftrace, "events");
 	if (!path)
 		die("malloc");
 
@@ -509,7 +509,7 @@ static void report_event_triggers(struct buffer_instance *instance)
 	enum event_iter_type type;
 	enum event_process processed = PROCESSED_NONE;
 
-	path = get_instance_file(instance, "events");
+	path = tracecmd_get_instance_file(instance->ftrace, "events");
 	if (!path)
 		die("malloc");
 
@@ -598,7 +598,7 @@ static void report_graph_funcs(struct buffer_instance *instance)
 {
 	char *path;
 
-	path = get_instance_file(instance, "set_graph_function");
+	path = tracecmd_get_instance_file(instance->ftrace, "set_graph_function");
 	if (!path)
 		die("malloc");
 
@@ -606,7 +606,7 @@ static void report_graph_funcs(struct buffer_instance *instance)
 	
 	tracecmd_put_tracing_file(path);
 
-	path = get_instance_file(instance, "set_graph_notrace");
+	path = tracecmd_get_instance_file(instance->ftrace, "set_graph_notrace");
 	if (!path)
 		die("malloc");
 
@@ -619,7 +619,7 @@ static void report_ftrace_filters(struct buffer_instance *instance)
 {
 	char *path;
 
-	path = get_instance_file(instance, "set_ftrace_filter");
+	path = tracecmd_get_instance_file(instance->ftrace, "set_ftrace_filter");
 	if (!path)
 		die("malloc");
 
@@ -627,7 +627,7 @@ static void report_ftrace_filters(struct buffer_instance *instance)
 	
 	tracecmd_put_tracing_file(path);
 
-	path = get_instance_file(instance, "set_ftrace_notrace");
+	path = tracecmd_get_instance_file(instance->ftrace, "set_ftrace_notrace");
 	if (!path)
 		die("malloc");
 
@@ -857,7 +857,7 @@ static void stat_instance(struct buffer_instance *instance)
 	if (instance != &top_instance) {
 		if (instance != first_instance)
 			printf("---------------\n");
-		printf("Instance: %s\n", instance->name);
+		printf("Instance: %s\n", tracecmd_get_instance_name(instance->ftrace));
 	}
 
 	report_plugin(instance);
@@ -882,6 +882,8 @@ void trace_stat (int argc, char **argv)
 	int status;
 	int c;
 
+	init_top_instance();
+
 	for (;;) {
 		c = getopt(argc-1, argv+1, "tB:");
 		if (c == -1)
-- 
2.23.0

[PATCH v18 05/18] trace-cmd: Add new library API for local CPU count

[Tzvetomir Stoyanov (VMware)]

In order to reuse the code, the function detecting the
number of local CPU is moved from trace-cmd application to
libtracecmd. The following new library API is introduced:
	int tracecmd_count_cpus(void);

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h  |  3 +++
 lib/trace-cmd/trace-util.c     | 49 ++++++++++++++++++++++++++++++++++
 tracecmd/include/trace-local.h |  2 --
 tracecmd/trace-agent.c         |  2 +-
 tracecmd/trace-profile.c       |  2 +-
 tracecmd/trace-record.c        | 46 +++----------------------------
 tracecmd/trace-stat.c          |  4 +--
 7 files changed, 59 insertions(+), 49 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 32182bc..f9ad823 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -427,6 +427,9 @@ void tracecmd_plog(const char *fmt, ...);
 void tracecmd_plog_error(const char *fmt, ...);
 int tracecmd_set_logfile(char *logfile);
 
+/* --- System --- */
+int tracecmd_count_cpus(void);
+
 /* --- Hack! --- */
 int tracecmd_blk_hack(struct tracecmd_input *handle);
 
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 582709f..2a121eb 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -1112,6 +1112,55 @@ int tracecmd_stack_tracer_status(int *status)
 	return 1; /* full success */
 }
 
+/**
+ * tracecmd_count_cpus - Get the number of CPUs in the system
+ *
+ * Returns the number of CPUs in the system, or 0 in case of an error
+ */
+int tracecmd_count_cpus(void)
+{
+	static int once;
+	char buf[1024];
+	int cpus = 0;
+	char *pbuf;
+	size_t *pn;
+	FILE *fp;
+	size_t n;
+	int r;
+
+	cpus = sysconf(_SC_NPROCESSORS_CONF);
+	if (cpus > 0)
+		return cpus;
+
+	if (!once) {
+		once++;
+		warning("sysconf could not determine number of CPUS");
+	}
+
+	/* Do the hack to figure out # of CPUS */
+	n = 1024;
+	pn = &n;
+	pbuf = buf;
+
+	fp = fopen("/proc/cpuinfo", "r");
+	if (!fp)
+		die("Can not read cpuinfo");
+
+	while ((r = getline(&pbuf, pn, fp)) >= 0) {
+		char *p;
+
+		if (strncmp(buf, "processor", 9) != 0)
+			continue;
+		for (p = buf+9; isspace(*p); p++)
+			;
+		if (*p == ':')
+			cpus++;
+	}
+	fclose(fp);
+
+	return cpus;
+}
+
 /*
  * tracecmd_write_file - Write in trace file
  * @file: Full name of the trace file.
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 3a05e9c..a51f0d0 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -243,8 +243,6 @@ void update_first_instance(struct buffer_instance *instance, int topt);
 
 void show_instance_file(struct buffer_instance *instance, const char *name);
 
-int count_cpus(void);
-
 /* moved from trace-cmd.h */
 void tracecmd_create_top_instance(char *name);
 void tracecmd_remove_instances(void);
diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c
index 93e3edf..1c6e0a3 100644
--- a/tracecmd/trace-agent.c
+++ b/tracecmd/trace-agent.c
@@ -203,7 +203,7 @@ static void agent_serve(unsigned int port)
 
 	signal(SIGCHLD, handle_sigchld);
 
-	nr_cpus = count_cpus();
+	nr_cpus = tracecmd_count_cpus();
 	page_size = getpagesize();
 
 	sd = make_vsock(port);
diff --git a/tracecmd/trace-profile.c b/tracecmd/trace-profile.c
index 231e381..cfae2a2 100644
--- a/tracecmd/trace-profile.c
+++ b/tracecmd/trace-profile.c
@@ -1314,7 +1314,7 @@ void trace_init_profile(struct tracecmd_input *handle, struct hook_list *hook,
 	 * system.
 	 */
 	if (!h->cpus)
-		h->cpus = count_cpus();
+		h->cpus = tracecmd_count_cpus();
 
 	list_head_init(&h->migrate_starts);
 	h->cpu_starts = malloc(sizeof(*h->cpu_starts) * h->cpus);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 3f4f55f..2d95d6f 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2726,46 +2726,6 @@ static void expand_event_list(void)
 		expand_event_instance(instance);
 }
 
-int count_cpus(void)
-{
-	FILE *fp;
-	char buf[1024];
-	int cpus = 0;
-	char *pbuf;
-	size_t *pn;
-	size_t n;
-	int r;
-
-	cpus = sysconf(_SC_NPROCESSORS_CONF);
-	if (cpus > 0)
-		return cpus;
-
-	warning("sysconf could not determine number of CPUS");
-
-	/* Do the hack to figure out # of CPUS */
-	n = 1024;
-	pn = &n;
-	pbuf = buf;
-
-	fp = fopen("/proc/cpuinfo", "r");
-	if (!fp)
-		die("Can not read cpuinfo");
-
-	while ((r = getline(&pbuf, pn, fp)) >= 0) {
-		char *p;
-
-		if (strncmp(buf, "processor", 9) != 0)
-			continue;
-		for (p = buf+9; isspace(*p); p++)
-			;
-		if (*p == ':')
-			cpus++;
-	}
-	fclose(fp);
-
-	return cpus;
-}
-
 static void finish(int sig)
 {
 	/* all done */
@@ -4489,7 +4449,7 @@ static void reset_clock(void)
 static void reset_cpu_mask(void)
 {
 	struct buffer_instance *instance;
-	int cpus = count_cpus();
+	int cpus = tracecmd_count_cpus();
 	int fullwords = (cpus - 1) / 32;
 	int bits = (cpus - 1) % 32 + 1;
 	int len = (fullwords + 1) * 9;
@@ -5045,7 +5005,7 @@ void init_top_instance(void)
 {
 	if (!top_instance.ftrace)
 		top_instance.ftrace = tracecmd_alloc_instance(NULL);
-	top_instance.cpu_count = count_cpus();
+	top_instance.cpu_count = tracecmd_count_cpus();
 	top_instance.flags = BUFFER_FL_KEEP;
 	tracecmd_init_instance(&top_instance);
 }
@@ -5242,7 +5202,7 @@ static void init_common_record_context(struct common_record_context *ctx,
 	memset(ctx, 0, sizeof(*ctx));
 	ctx->instance = &top_instance;
 	ctx->curr_cmd = curr_cmd;
-	local_cpu_count = count_cpus();
+	local_cpu_count = tracecmd_count_cpus();
 	init_top_instance();
 }
 
diff --git a/tracecmd/trace-stat.c b/tracecmd/trace-stat.c
index 5cc9d28..bb6e40b 100644
--- a/tracecmd/trace-stat.c
+++ b/tracecmd/trace-stat.c
@@ -737,7 +737,7 @@ static void report_cpumask(struct buffer_instance *instance)
 	cont = strstrip(str);
 
 	/* check to make sure all CPUs on this machine are set */
-	cpus = count_cpus();
+	cpus = tracecmd_count_cpus();
 
 	for (i = strlen(cont) - 1; i >= 0 && cpus > 0; i--) {
 		if (cont[i] == ',')
@@ -896,7 +896,7 @@ void trace_stat (int argc, char **argv)
 			instance = create_instance(optarg);
 			if (!instance)
 				die("Failed to create instance");
-			add_instance(instance, count_cpus());
+			add_instance(instance, tracecmd_count_cpus());
 			/* top instance requires direct access */
 			if (!topt && is_top_instance(first_instance))
 				first_instance = instance;
-- 
2.23.0

[PATCH v18 06/18] trace-cmd: Add new library API for reading ftrace buffers

[Tzvetomir Stoyanov (VMware)]

A new libtracecmd API is introduced:

	int tracecmd_iterate_raw_events(struct tep_handle *tep,
					struct tracecmd_instance *instance,
					int (*callback)(struct tep_event *,
						   	struct tep_record *,
						   	int, void *context),
					void *callback_context);

It reads events from trace_pipe_raw, per cpu ftrace buffer, and calls a user
callback for each of them. The API is instance aware.
The new API can be used to search for a specific event, or sequence of events,
in a ftrace instance.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h |   8 +++
 lib/trace-cmd/trace-util.c    | 115 ++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index f9ad823..c0b9f4b 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -380,6 +380,14 @@ int tracecmd_alloc_instance_clock(struct tracecmd_instance *instance,
 char *tracecmd_get_instance_clock(struct tracecmd_instance *instance);
 int tracecmd_set_clock(struct tracecmd_instance *instance, char **old_clock);
 
+int tracecmd_iterate_raw_events(struct tep_handle *tep,
+				struct tracecmd_instance *instance,
+				   int (*callback)(struct tep_event *,
+						   struct tep_record *,
+						   int, void *context),
+				void *callback_context);
+
+
 
 /* --- Plugin handling --- */
 extern struct tep_plugin_option trace_ftrace_options[];
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 2a121eb..75ec5a3 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -1194,3 +1194,118 @@ int tracecmd_write_file(const char *file, const char *str, const char *type)
 	}
 	return ret;
 }
+
+static int
+get_events_in_page(struct tep_handle *tep, void *page,
+		   int size, int cpu,
+		   int (*callback)(struct tep_event *,
+				   struct tep_record *,
+				   int, void *),
+		   void *callback_context)
+{
+	struct tep_record *last_record = NULL;
+	struct tep_event *event = NULL;
+	struct tep_record *record;
+	int id, cnt = 0;
+
+	if (size <= 0)
+		return 0;
+
+	while (true) {
+		event = NULL;
+		record = tracecmd_read_page_record(tep, page, size,
+						   last_record);
+		if (!record)
+			break;
+		free_record(last_record);
+		id = tep_data_type(tep, record);
+		event = tep_find_event(tep, id);
+		if (event && callback) {
+			if (callback(event, record, cpu, callback_context))
+				break;
+		}
+		last_record = record;
+	}
+	free_record(last_record);
+
+	return cnt;
+}
+
+/*
+ * tracecmd_iterate_raw_events - Iterate through events in trace_pipe_raw
+ *				 per CPU trace files
+ * @tep: a handle to the trace event parser context
+ * @instance: ftrace instance, can be NULL for the top instance
+ * @callback: A user function, called for each record from the file
+ * @callback_context: A custom context, passed to the user callback function
+ *
+ * If the @callback returns non-zero, the iteration stops - in that case all
+ * records from the current page will be lost from future reads
+ *
+ * Returns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_iterate_raw_events(struct tep_handle *tep,
+				struct tracecmd_instance *instance,
+				int (*callback)(struct tep_event *,
+						struct tep_record *,
+						int, void *),
+				void *callback_context)
+{
+	unsigned int p_size;
+	struct dirent *dent;
+	char file[PATH_MAX];
+	void *page = NULL;
+	struct stat st;
+	char *path;
+	DIR *dir;
+	int ret;
+	int cpu;
+	int fd;
+	int r;
+
+	p_size = getpagesize();
+	path = tracecmd_get_instance_file(instance, "per_cpu");
+	if (!path)
+		return -1;
+	dir = opendir(path);
+	if (!dir) {
+		ret = -1;
+		goto error;
+	}
+	page = malloc(p_size);
+	if (!page) {
+		ret = -1;
+		goto error;
+	}
+	while ((dent = readdir(dir))) {
+		const char *name = dent->d_name;
+
+		if (strlen(name) < 4 || strncmp(name, "cpu", 3) != 0)
+			continue;
+		cpu = atoi(name + 3);
+		sprintf(file, "%s/%s", path, name);
+		ret = stat(file, &st);
+		if (ret < 0 || !S_ISDIR(st.st_mode))
+			continue;
+
+		sprintf(file, "%s/%s/trace_pipe_raw", path, name);
+		fd = open(file, O_RDONLY | O_NONBLOCK);
+		if (fd < 0)
+			continue;
+		do {
+			r = read(fd, page, p_size);
+			if (r > 0)
+				get_events_in_page(tep, page, r, cpu,
+						   callback, callback_context);
+		} while (r > 0);
+		close(fd);
+	}
+	ret = 0;
+
+error:
+	if (dir)
+		closedir(dir);
+	free(page);
+	tracecmd_put_tracing_file(path);
+	return ret;
+}
-- 
2.23.0

[PATCH v18 07/18] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

In order to match host and guest events, a mapping between guest VCPU
and the host task, running this VCPU is needed. Extended existing
struct guest to hold such mapping and added logic in read_qemu_guests()
function to initialize it. Implemented a new internal API,
get_guest_vcpu_pid(), to retrieve VCPU-task mapping for given VM.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 tracecmd/include/trace-local.h |  2 ++
 tracecmd/trace-record.c        | 54 ++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index a51f0d0..51abef1 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -243,6 +243,8 @@ void update_first_instance(struct buffer_instance *instance, int topt);
 
 void show_instance_file(struct buffer_instance *instance, const char *name);
 
+int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu);
+
 /* moved from trace-cmd.h */
 void tracecmd_create_top_instance(char *name);
 void tracecmd_remove_instances(void);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 2d95d6f..7a3d687 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2873,10 +2873,12 @@ static bool is_digits(const char *s)
 	return true;
 }
 
+#define VCPUS_MAX 256
 struct guest {
 	char *name;
 	int cid;
 	int pid;
+	int cpu_pid[VCPUS_MAX];
 };
 
 static struct guest *guests;
@@ -2894,6 +2896,43 @@ static char *get_qemu_guest_name(char *arg)
 	return arg;
 }
 
+static void read_qemu_guests_pids(char *guest_task, struct guest *guest)
+{
+	struct dirent *entry;
+	char path[PATH_MAX];
+	char *buf = NULL;
+	size_t n = 0;
+	int vcpu;
+	DIR *dir;
+	FILE *f;
+
+	snprintf(path, sizeof(path), "/proc/%s/task", guest_task);
+	dir = opendir(path);
+	if (!dir)
+		return;
+
+	while ((entry = readdir(dir))) {
+		if (!(entry->d_type == DT_DIR && is_digits(entry->d_name)))
+			continue;
+
+		snprintf(path, sizeof(path), "/proc/%s/task/%s/comm",
+			 guest_task, entry->d_name);
+		f = fopen(path, "r");
+		if (!f)
+			continue;
+
+		if (getline(&buf, &n, f) >= 0 &&
+		    strncmp(buf, "CPU ", 4) == 0) {
+			vcpu = atoi(buf + 4);
+			if (vcpu >= 0 && vcpu < VCPUS_MAX)
+				guest->cpu_pid[vcpu] = atoi(entry->d_name);
+		}
+
+		fclose(f);
+	}
+	free(buf);
+}
+
 static void read_qemu_guests(void)
 {
 	static bool initialized;
@@ -2957,6 +2996,8 @@ static void read_qemu_guests(void)
 		if (!is_qemu)
 			goto next;
 
+		read_qemu_guests_pids(entry->d_name, &guest);
+
 		guests = realloc(guests, (guests_len + 1) * sizeof(*guests));
 		if (!guests)
 			die("Can not allocate guest buffer");
@@ -3002,6 +3043,19 @@ static char *parse_guest_name(char *guest, int *cid, int *port)
 	return guest;
 }
 
+int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu)
+{
+	int i;
+
+	if (!guests || guest_vcpu >= VCPUS_MAX)
+		return -1;
+
+	for (i = 0; i < guests_len; i++)
+		if (guest_cid == guests[i].cid)
+			return guests[i].cpu_pid[guest_vcpu];
+	return -1;
+}
+
 static void set_prio(int prio)
 {
 	struct sched_param sp;
-- 
2.23.0

[PATCH v18 08/18] trace-cmd: Implement new API tracecmd_add_option_v()

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

A new tracecmd API tracecmd_add_option_v() is introduced.
It adds new option in trace.dat, similar to tracecmd_add_option(),
but the option's data is passed as list of buffers. The standard
struct iovec is used as input parameter, containing the option's
data buffers.

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 include/trace-cmd/trace-cmd.h    |   5 ++
 include/traceevent/event-parse.h |   1 +
 lib/trace-cmd/trace-output.c     | 117 +++++++++++++++++++++++++++----
 3 files changed, 108 insertions(+), 15 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index c0b9f4b..9a2b7db 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -261,11 +261,16 @@ struct tracecmd_output *tracecmd_create_init_file_override(const char *output_fi
 struct tracecmd_option *tracecmd_add_option(struct tracecmd_output *handle,
 					    unsigned short id, int size,
 					    const void *data);
+struct tracecmd_option *
+tracecmd_add_option_v(struct tracecmd_output *handle,
+		      unsigned short id, const struct iovec *vector, int count);
+
 struct tracecmd_option *tracecmd_add_buffer_option(struct tracecmd_output *handle,
 						   const char *name, int cpus);
 
 int tracecmd_write_cpus(struct tracecmd_output *handle, int cpus);
 int tracecmd_write_options(struct tracecmd_output *handle);
+int tracecmd_append_options(struct tracecmd_output *handle);
 int tracecmd_update_option(struct tracecmd_output *handle,
 			   struct tracecmd_option *option, int size,
 			   const void *data);
diff --git a/include/traceevent/event-parse.h b/include/traceevent/event-parse.h
index a77af4c..30e06a7 100644
--- a/include/traceevent/event-parse.h
+++ b/include/traceevent/event-parse.h
@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <regex.h>
 #include <string.h>
+#include <sys/uio.h>
 
 #include "traceevent/trace-seq.h"
 
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index be4d3f5..c701c8c 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -950,21 +950,27 @@ static struct tracecmd_output *create_file(const char *output_file,
 }
 
 /**
- * tracecmd_add_option - add options to the file
+ * tracecmd_add_option_v - add options to the file
  * @handle: the output file handle name
  * @id: the id of the option
  * @size: the size of the option data
- * @data: the data to write to the file.
+ * @data: the data to write to the file
+ * @vector: array of vectors, pointing to the data to write in the file
+ * @count: number of items in the vector array
+ *
  *
  * Returns handle to update option if needed.
  *  Just the content can be updated, with smaller or equal to
  *  content than the specified size.
  */
 struct tracecmd_option *
-tracecmd_add_option(struct tracecmd_output *handle,
-		    unsigned short id, int size, const void *data)
+tracecmd_add_option_v(struct tracecmd_output *handle,
+		      unsigned short id, const struct iovec *vector, int count)
+
 {
 	struct tracecmd_option *option;
+	char *data = NULL;
+	int i, size = 0;
 
 	/*
 	 * We can only add options before they were written.
@@ -973,32 +979,63 @@ tracecmd_add_option(struct tracecmd_output *handle,
 	if (handle->options_written)
 		return NULL;
 
-	handle->nr_options++;
+	for (i = 0; i < count; i++)
+		size += vector[i].iov_len;
+	/* Some IDs (like TRACECMD_OPTION_TRACECLOCK) pass vector with 0 / NULL data */
+	if (size) {
+		data = malloc(size);
+		if (!data) {
+			warning("Insufficient memory");
+			return NULL;
+		}
+	}
 
 	option = malloc(sizeof(*option));
 	if (!option) {
 		warning("Could not allocate space for option");
+		free(data);
 		return NULL;
 	}
 
-	option->id = id;
-	option->size = size;
-	option->data = malloc(size);
-	if (!option->data) {
-		warning("Insufficient memory");
-		free(option);
-		return NULL;
+	handle->nr_options++;
+	option->data = data;
+	for (i = 0; i < count; i++) {
+		if (vector[i].iov_base && vector[i].iov_len) {
+			memcpy(data, vector[i].iov_base, vector[i].iov_len);
+			data += vector[i].iov_len;
+		}
 	}
 
-	/* Some IDs (like TRACECMD_OPTION_TRACECLOCK) pass 0 / NULL data */
-	if (size)
-		memcpy(option->data, data, size);
+	option->size = size;
+	option->id = id;
 
 	list_add_tail(&option->list, &handle->options);
 
 	return option;
 }
 
+/**
+ * tracecmd_add_option - add options to the file
+ * @handle: the output file handle name
+ * @id: the id of the option
+ * @size: the size of the option data
+ * @data: the data to write to the file
+ *
+ * Returns handle to update option if needed
+ *  Just the content can be updated, with smaller or equal to
+ *  content than the specified size
+ */
+struct tracecmd_option *
+tracecmd_add_option(struct tracecmd_output *handle,
+		    unsigned short id, int size, const void *data)
+{
+	struct iovec vect;
+
+	vect.iov_base = (void *) data;
+	vect.iov_len = size;
+	return tracecmd_add_option_v(handle, id, &vect, 1);
+}
+
 int tracecmd_write_cpus(struct tracecmd_output *handle, int cpus)
 {
 	cpus = convert_endian_4(handle, cpus);
@@ -1046,6 +1083,56 @@ int tracecmd_write_options(struct tracecmd_output *handle)
 	return 0;
 }
 
+int tracecmd_append_options(struct tracecmd_output *handle)
+{
+	struct tracecmd_option *options;
+	unsigned short option;
+	unsigned short endian2;
+	unsigned int endian4;
+	off_t offset;
+	int r;
+
+	/* If already written, ignore */
+	if (handle->options_written)
+		return 0;
+
+	if (lseek64(handle->fd, 0, SEEK_END) == (off_t)-1)
+		return -1;
+	offset = lseek64(handle->fd, -2, SEEK_CUR);
+	if (offset == (off_t)-1)
+		return -1;
+
+	r = pread(handle->fd, &option, 2, offset);
+	if (r != 2 || option != TRACECMD_OPTION_DONE)
+		return -1;
+
+	list_for_each_entry(options, &handle->options, list) {
+		endian2 = convert_endian_2(handle, options->id);
+		if (do_write_check(handle, &endian2, 2))
+			return -1;
+
+		endian4 = convert_endian_4(handle, options->size);
+		if (do_write_check(handle, &endian4, 4))
+			return -1;
+
+		/* Save the data location in case it needs to be updated */
+		options->offset = lseek64(handle->fd, 0, SEEK_CUR);
+
+		if (do_write_check(handle, options->data,
+				   options->size))
+			return -1;
+	}
+
+	option = TRACECMD_OPTION_DONE;
+
+	if (do_write_check(handle, &option, 2))
+		return -1;
+
+	handle->options_written = 1;
+
+	return 0;
+}
+
 int tracecmd_update_option(struct tracecmd_output *handle,
 			   struct tracecmd_option *option, int size,
 			   const void *data)
-- 
2.23.0

[PATCH v18 09/18] trace-cmd: Add new API to generate a unique ID of the tracing session

[Tzvetomir Stoyanov (VMware)]

A new libtracecmd API is implemented:
	unsigned long long tracecmd_generate_traceid(void);
At trace-cmd init phase a unique ID, used for the current tracing session.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h  |  1 +
 lib/trace-cmd/trace-util.c     | 37 ++++++++++++++++++++++++++++++++++
 tracecmd/include/trace-local.h |  1 +
 tracecmd/trace-record.c        |  1 +
 4 files changed, 40 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 9a2b7db..ad69313 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -441,6 +441,7 @@ void tracecmd_plog_error(const char *fmt, ...);
 int tracecmd_set_logfile(char *logfile);
 
 /* --- System --- */
+unsigned long long tracecmd_generate_traceid(void);
 int tracecmd_count_cpus(void);
 
 /* --- Hack! --- */
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 75ec5a3..fabd558 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -18,6 +18,8 @@
 #include <sys/mount.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/sysinfo.h>
+#include <time.h>
 
 #include "trace-cmd.h"
 #include "event-utils.h"
@@ -1309,3 +1311,38 @@ error:
 	tracecmd_put_tracing_file(path);
 	return ret;
 }
+
+#define FNV_64_PRIME 0x100000001b3ULL
+/*
+ * tracecmd_generate_traceid - Generate a unique ID, used to identify
+ *			       the current tracing session
+ *
+ * Returns unique ID
+ */
+unsigned long long tracecmd_generate_traceid(void)
+{
+	unsigned long long hash = 0;
+	unsigned char *ustr;
+	struct sysinfo sinfo;
+	struct timespec ts;
+	char *str = NULL;
+
+	clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
+	sysinfo(&sinfo);
+	asprintf(&str, "%ld %ld %ld %ld %ld %ld %ld %ld %d",
+		 ts.tv_sec, ts.tv_nsec,
+		 sinfo.loads[0], sinfo.loads[1], sinfo.loads[2],
+		 sinfo.freeram, sinfo.sharedram, sinfo.freeswap,
+		 sinfo.procs);
+	if (!str)
+		return 0;
+	ustr = (unsigned char *)str;
+	hash = 0;
+	while (*ustr) {
+		hash ^= (unsigned long long)*ustr++;
+		hash *= FNV_64_PRIME;
+	}
+
+	free(str);
+	return hash;
+}
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 51abef1..6203e0d 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -182,6 +182,7 @@ struct pid_addr_maps {
 struct buffer_instance {
 	struct buffer_instance	*next;
 	struct tracecmd_instance	*ftrace;
+	unsigned long long	trace_id;
 	char			*cpumask;
 	struct event_list	*events;
 	struct event_list	**event_next;
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 7a3d687..7089f7b 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -5061,6 +5061,7 @@ void init_top_instance(void)
 		top_instance.ftrace = tracecmd_alloc_instance(NULL);
 	top_instance.cpu_count = tracecmd_count_cpus();
 	top_instance.flags = BUFFER_FL_KEEP;
+	top_instance.trace_id = tracecmd_generate_traceid();
 	tracecmd_init_instance(&top_instance);
 }
 
-- 
2.23.0

[PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file

[Tzvetomir Stoyanov (VMware)]

The ID of the current tracing session is stored in the trace.dat file.
A new file option is introduced:
	TRACECMD_OPTION_TRACEID
The data is stored in the file as NULL terminated string:
	"\nTraceID: %llu\n"
A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
	unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h |  2 ++
 lib/trace-cmd/trace-input.c   | 25 +++++++++++++++++++++++++
 tracecmd/trace-record.c       | 15 +++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index ad69313..6cc2913 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -86,6 +86,7 @@ enum {
 	TRACECMD_OPTION_CPUCOUNT,
 	TRACECMD_OPTION_VERSION,
 	TRACECMD_OPTION_PROCMAPS,
+	TRACECMD_OPTION_TRACEID,
 };
 
 enum {
@@ -128,6 +129,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
 void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
 void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
 unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
+unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
 
 void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
 
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 91362f3..40d9825 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -79,6 +79,7 @@ struct tracecmd_input {
 	struct tep_plugin_list	*plugin_list;
 	struct tracecmd_input	*parent;
 	unsigned long		flags;
+	unsigned long long	trace_id;
 	int			fd;
 	int			long_size;
 	int			page_size;
@@ -2169,6 +2170,15 @@ static void procmap_free(struct pid_addr_maps *maps)
 	free(maps);
 }
 
+static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
+{
+
+	if (sscanf(buf, "%*s %llu", &handle->trace_id) == 1)
+		return 0;
+
+	return -1;
+}
+
 #define STR_PROCMAP_LINE_MAX	(PATH_MAX+22)
 static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
 {
@@ -2406,6 +2416,10 @@ static int handle_options(struct tracecmd_input *handle)
 			if (buf[size-1] == '\0')
 				trace_pid_map_load(handle, buf);
 			break;
+		case TRACECMD_OPTION_TRACEID:
+			if (buf[size-1] == '\0')
+				trace_traceid_load(handle, buf);
+			break;
 		default:
 			warning("unknown option %d", option);
 			break;
@@ -3507,3 +3521,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
 {
 	handle->show_data_func = func;
 }
+
+/**
+ * tracecmd_get_traceid - get the trace id of the session
+ * @handle: input handle for the trace.dat file
+ *
+ * Returns the trace id, written in the trace file
+ */
+unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
+{
+	return handle->trace_id;
+}
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 7089f7b..b65aeb2 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3714,6 +3714,19 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
 	trace_seq_destroy(&s);
 }
 
+static void
+add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
+{
+	char *str = NULL;
+	int len;
+
+	len = asprintf(&str, "\nTraceID: %llu\n", instance->trace_id);
+	if (len < 1)
+		return;
+	tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID, len + 1, str);
+	free(str);
+}
+
 static void
 add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
 {
@@ -3817,6 +3830,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
 	add_option_hooks(handle);
 	add_uname(handle);
 	add_version(handle);
+	if (!no_top_instance())
+		add_trace_id(handle, &top_instance);
 }
 
 static void write_guest_file(struct buffer_instance *instance)
-- 
2.23.0

[PATCH v18 11/18] trace-cmd: Exchange tracing IDs between host and guest

[Tzvetomir Stoyanov (VMware)]

Extend the trace request and trace reply messages, to include also
the IDs of host and guest tracing sessions. Those IDs are used to
unambiguously match the tracing sessions, when reading trace.dat files.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h  | 12 ++++++++----
 lib/trace-cmd/trace-msg.c      | 31 +++++++++++++++++++++++--------
 tracecmd/include/trace-local.h |  4 +++-
 tracecmd/trace-agent.c         | 12 +++++++-----
 tracecmd/trace-record.c        | 12 +++++++++---
 5 files changed, 50 insertions(+), 21 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 6cc2913..23415e4 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -353,16 +353,20 @@ bool tracecmd_msg_done(struct tracecmd_msg_handle *msg_handle);
 void tracecmd_msg_set_done(struct tracecmd_msg_handle *msg_handle);
 
 int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
-				int argc, char **argv, bool use_fifos);
+				int argc, char **argv, bool use_fifos,
+				unsigned long long trace_id);
 int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
-				int *argc, char ***argv, bool *use_fifos);
+				int *argc, char ***argv, bool *use_fifos,
+				unsigned long long *trace_id);
 
 int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int nr_cpus, int page_size,
-				 unsigned int *ports, bool use_fifos);
+				 unsigned int *ports, bool use_fifos,
+				 unsigned long long trace_id);
 int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int *nr_cpus, int *page_size,
-				 unsigned int **ports, bool *use_fifos);
+				 unsigned int **ports, bool *use_fifos,
+				 unsigned long long *trace_id);
 /* --- ftrace instances --- */
 
 struct tracecmd_instance;
diff --git a/lib/trace-cmd/trace-msg.c b/lib/trace-cmd/trace-msg.c
index 9c8a690..a34297f 100644
--- a/lib/trace-cmd/trace-msg.c
+++ b/lib/trace-cmd/trace-msg.c
@@ -63,12 +63,14 @@ struct tracecmd_msg_rinit {
 struct tracecmd_msg_trace_req {
 	be32 flags;
 	be32 argc;
+	u64 trace_id;
 } __attribute__((packed));
 
 struct tracecmd_msg_trace_resp {
 	be32 flags;
 	be32 cpus;
 	be32 page_size;
+	u64 trace_id;
 } __attribute__((packed));
 
 struct tracecmd_msg_header {
@@ -811,7 +813,8 @@ int tracecmd_msg_wait_close_resp(struct tracecmd_msg_handle *msg_handle)
 	return tracecmd_msg_wait_for_cmd(msg_handle, MSG_CLOSE_RESP);
 }
 
-static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv, bool use_fifos)
+static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv,
+			  bool use_fifos, unsigned long long trace_id)
 {
 	size_t args_size = 0;
 	char *p;
@@ -823,6 +826,7 @@ static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv, bool
 	msg->hdr.size = htonl(ntohl(msg->hdr.size) + args_size);
 	msg->trace_req.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
 	msg->trace_req.argc = htonl(argc);
+	msg->trace_req.trace_id = htonll(trace_id);
 	msg->buf = calloc(args_size, 1);
 	if (!msg->buf)
 		return -ENOMEM;
@@ -835,13 +839,15 @@ static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv, bool
 }
 
 int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
-				int argc, char **argv, bool use_fifos)
+				int argc, char **argv, bool use_fifos,
+				unsigned long long trace_id)
 {
 	struct tracecmd_msg msg;
 	int ret;
 
 	tracecmd_msg_init(MSG_TRACE_REQ, &msg);
-	ret = make_trace_req(&msg, argc, argv, use_fifos);
+	ret = make_trace_req(&msg, argc, argv,
+			     use_fifos, trace_id);
 	if (ret < 0)
 		return ret;
 
@@ -854,7 +860,8 @@ int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
   *     free(argv);
   */
 int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
-				int *argc, char ***argv, bool *use_fifos)
+				int *argc, char ***argv, bool *use_fifos,
+				unsigned long long *trace_id)
 {
 	struct tracecmd_msg msg;
 	char *p, *buf_end, **args;
@@ -901,6 +908,7 @@ int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
 	*argc = nr_args;
 	*argv = args;
 	*use_fifos = ntohl(msg.trace_req.flags) & MSG_TRACE_USE_FIFOS;
+	*trace_id = ntohll(msg.trace_req.trace_id);
 
 	/*
 	 * On success we're passing msg.buf to the caller through argv[0] so we
@@ -921,7 +929,8 @@ out:
 }
 
 static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus,
-			   unsigned int *ports, bool use_fifos)
+			   unsigned int *ports, bool use_fifos,
+			   unsigned long long trace_id)
 {
 	int data_size;
 
@@ -935,19 +944,22 @@ static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus,
 	msg->trace_resp.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
 	msg->trace_resp.cpus = htonl(nr_cpus);
 	msg->trace_resp.page_size = htonl(page_size);
+	msg->trace_resp.trace_id = htonll(trace_id);
 
 	return 0;
 }
 
 int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int nr_cpus, int page_size,
-				 unsigned int *ports, bool use_fifos)
+				 unsigned int *ports, bool use_fifos,
+				 unsigned long long trace_id)
 {
 	struct tracecmd_msg msg;
 	int ret;
 
 	tracecmd_msg_init(MSG_TRACE_RESP, &msg);
-	ret = make_trace_resp(&msg, page_size, nr_cpus, ports, use_fifos);
+	ret = make_trace_resp(&msg, page_size, nr_cpus, ports,
+			      use_fifos, trace_id);
 	if (ret < 0)
 		return ret;
 
@@ -956,13 +968,15 @@ int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 
 int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int *nr_cpus, int *page_size,
-				 unsigned int **ports, bool *use_fifos)
+				 unsigned int **ports, bool *use_fifos,
+				 unsigned long long *trace_id)
 {
 	struct tracecmd_msg msg;
 	char *p, *buf_end;
 	ssize_t buf_len;
 	int i, ret;
 
+	memset(&msg, 0, sizeof(msg));
 	ret = tracecmd_msg_recv(msg_handle->fd, &msg);
 	if (ret < 0)
 		return ret;
@@ -981,6 +995,7 @@ int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 	*use_fifos = ntohl(msg.trace_resp.flags) & MSG_TRACE_USE_FIFOS;
 	*nr_cpus = ntohl(msg.trace_resp.cpus);
 	*page_size = ntohl(msg.trace_resp.page_size);
+	*trace_id = ntohll(msg.trace_resp.trace_id);
 	*ports = calloc(*nr_cpus, sizeof(**ports));
 	if (!*ports) {
 		ret = -ENOMEM;
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 6203e0d..90933cc 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -98,7 +98,9 @@ void trace_usage(int argc, char **argv);
 
 int trace_record_agent(struct tracecmd_msg_handle *msg_handle,
 		       int cpus, int *fds,
-		       int argc, char **argv, bool use_fifos);
+		       int argc, char **argv,
+		       bool use_fifos,
+		       unsigned long long trace_id);
 
 struct hook_list;
 
diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c
index 1c6e0a3..cc330b7 100644
--- a/tracecmd/trace-agent.c
+++ b/tracecmd/trace-agent.c
@@ -128,6 +128,7 @@ cleanup:
 static void agent_handle(int sd, int nr_cpus, int page_size)
 {
 	struct tracecmd_msg_handle *msg_handle;
+	unsigned long long trace_id;
 	unsigned int *ports;
 	char **argv = NULL;
 	int argc = 0;
@@ -144,7 +145,8 @@ static void agent_handle(int sd, int nr_cpus, int page_size)
 	if (!msg_handle)
 		die("Failed to allocate message handle");
 
-	ret = tracecmd_msg_recv_trace_req(msg_handle, &argc, &argv, &use_fifos);
+	ret = tracecmd_msg_recv_trace_req(msg_handle, &argc, &argv,
+					  &use_fifos, &trace_id);
 	if (ret < 0)
 		die("Failed to receive trace request");
 
@@ -153,13 +155,13 @@ static void agent_handle(int sd, int nr_cpus, int page_size)
 
 	if (!use_fifos)
 		make_vsocks(nr_cpus, fds, ports);
-
+	trace_id = tracecmd_generate_traceid();
 	ret = tracecmd_msg_send_trace_resp(msg_handle, nr_cpus, page_size,
-					   ports, use_fifos);
+					   ports, use_fifos, trace_id);
 	if (ret < 0)
 		die("Failed to send trace response");
-
-	trace_record_agent(msg_handle, nr_cpus, fds, argc, argv, use_fifos);
+	trace_record_agent(msg_handle, nr_cpus, fds, argc, argv,
+			   use_fifos, trace_id);
 
 	free(argv[0]);
 	free(argv);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index b65aeb2..4bd9b7a 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3505,12 +3505,16 @@ static void connect_to_agent(struct buffer_instance *instance)
 		die("Failed to allocate message handle");
 
 	ret = tracecmd_msg_send_trace_req(msg_handle, instance->argc,
-					  instance->argv, use_fifos);
+					  instance->argv, use_fifos,
+					  top_instance.trace_id);
+
 	if (ret < 0)
 		die("Failed to send trace request");
 
 	ret = tracecmd_msg_recv_trace_resp(msg_handle, &nr_cpus, &page_size,
-					   &ports, &use_fifos);
+					   &ports, &use_fifos,
+					   &instance->trace_id);
+
 	if (ret < 0)
 		die("Failed to receive trace response");
 
@@ -6116,7 +6120,8 @@ void trace_record(int argc, char **argv)
 int trace_record_agent(struct tracecmd_msg_handle *msg_handle,
 		       int cpus, int *fds,
 		       int argc, char **argv,
-		       bool use_fifos)
+		       bool use_fifos,
+		       unsigned long long trace_id)
 {
 	struct common_record_context ctx;
 	char **argv_plus;
@@ -6146,6 +6151,7 @@ int trace_record_agent(struct tracecmd_msg_handle *msg_handle,
 	ctx.instance->flags |= BUFFER_FL_AGENT;
 	ctx.instance->msg_handle = msg_handle;
 	msg_handle->version = V3_PROTOCOL;
+	top_instance.trace_id = trace_id;
 	record_trace(argc, argv, &ctx);
 
 	free(argv_plus);
-- 
2.23.0

[PATCH v18 12/18] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT

[Tzvetomir Stoyanov (VMware)]

From: Tzvetomir Stoyanov <tstoyanov@vmware.com>

The TRACECMD_OPTION_TIME_SHIFT is used when synchronizing trace time stamps between
two trace.dat files. It contains multiple long long (time, offset) pairs, describing
time stamps _offset_, measured in the given local _time_. The content of the option
buffer is:
 8 bytes - long long integer, ID of the tracing session
 4 bytes - integer, count of timestamp offsets
 long long array of size _count_, local time in which the offset is measured
 long long array of size _count_, offset of the time stamps

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
---
 include/trace-cmd/trace-cmd.h |   3 +
 lib/trace-cmd/trace-input.c   | 182 +++++++++++++++++++++++++++++++++-
 2 files changed, 183 insertions(+), 2 deletions(-)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index 23415e4..b06a0c3 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -87,6 +87,7 @@ enum {
 	TRACECMD_OPTION_VERSION,
 	TRACECMD_OPTION_PROCMAPS,
 	TRACECMD_OPTION_TRACEID,
+	TRACECMD_OPTION_TIME_SHIFT,
 };
 
 enum {
@@ -130,6 +131,8 @@ void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
 void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
 unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
 unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
+unsigned long long tracecmd_get_tsync_peer(struct tracecmd_input *handle);
+int tracecmd_enable_tsync(struct tracecmd_input *handle, bool enable);
 
 void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
 
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 40d9825..e8db876 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -74,6 +74,18 @@ struct input_buffer_instance {
 	size_t			offset;
 };
 
+struct ts_offset_sample {
+	long long	time;
+	long long	offset;
+};
+
+struct host_trace_info {
+	bool			sync_enable;
+	unsigned long long	trace_id;
+	int			ts_samples_count;
+	struct ts_offset_sample	*ts_samples;
+};
+
 struct tracecmd_input {
 	struct tep_handle	*pevent;
 	struct tep_plugin_list	*plugin_list;
@@ -92,6 +104,7 @@ struct tracecmd_input {
 	bool			use_pipe;
 	struct cpu_data 	*cpu_data;
 	long long		ts_offset;
+	struct host_trace_info	host;
 	double			ts2secs;
 	char *			cpustats;
 	char *			uname;
@@ -1072,6 +1085,69 @@ static void free_next(struct tracecmd_input *handle, int cpu)
 	free_record(record);
 }
 
+static inline unsigned long long
+timestamp_correction_calc(unsigned long long ts, struct ts_offset_sample *min,
+			  struct ts_offset_sample *max)
+{
+	long long offset = ((long long)ts - min->time) *
+			   (max->offset - min->offset);
+	long long delta = max->time - min->time;
+	long long tscor = min->offset +
+			(offset + delta / 2) / delta;
+
+	if (tscor < 0)
+		return ts - llabs(tscor);
+
+	return ts + tscor;
+}
+
+static unsigned long long timestamp_correct(unsigned long long ts,
+					    struct tracecmd_input *handle)
+{
+	struct host_trace_info	*host = &handle->host;
+	int min, mid, max;
+
+	if (handle->ts_offset)
+		return ts + handle->ts_offset;
+
+	if (!host->sync_enable)
+		return ts;
+
+	/* We have one sample, nothing to calc here */
+	if (host->ts_samples_count == 1)
+		return ts + host->ts_samples[0].offset;
+
+	/* We have two samples, nothing to search here */
+	if (host->ts_samples_count == 2)
+		return timestamp_correction_calc(ts, &host->ts_samples[0],
+						 &host->ts_samples[1]);
+
+	/* We have more than two samples */
+	if (ts <= host->ts_samples[0].time)
+		return timestamp_correction_calc(ts,
+						 &host->ts_samples[0],
+						 &host->ts_samples[1]);
+	else if (ts >= host->ts_samples[host->ts_samples_count-1].time)
+		return timestamp_correction_calc(ts,
+						 &host->ts_samples[host->ts_samples_count-2],
+						 &host->ts_samples[host->ts_samples_count-1]);
+	min = 0;
+	max = host->ts_samples_count-1;
+	mid = (min + max)/2;
+	while (min <= max) {
+		if (ts < host->ts_samples[mid].time)
+			max = mid - 1;
+		else if (ts > host->ts_samples[mid].time)
+			min = mid + 1;
+		else
+			break;
+		mid = (min + max)/2;
+	}
+
+	return timestamp_correction_calc(ts, &host->ts_samples[mid],
+					 &host->ts_samples[mid+1]);
+}
+
 /*
  * Page is mapped, now read in the page header info.
  */
@@ -1093,7 +1169,7 @@ static int update_page_info(struct tracecmd_input *handle, int cpu)
 		    kbuffer_subbuffer_size(kbuf));
 		return -1;
 	}
-	handle->cpu_data[cpu].timestamp = kbuffer_timestamp(kbuf) + handle->ts_offset;
+	handle->cpu_data[cpu].timestamp = timestamp_correct(kbuffer_timestamp(kbuf), handle);
 
 	if (handle->ts2secs)
 		handle->cpu_data[cpu].timestamp *= handle->ts2secs;
@@ -1820,7 +1896,7 @@ read_again:
 		goto read_again;
 	}
 
-	handle->cpu_data[cpu].timestamp = ts + handle->ts_offset;
+	handle->cpu_data[cpu].timestamp = timestamp_correct(ts, handle);
 
 	if (handle->ts2secs) {
 		handle->cpu_data[cpu].timestamp *= handle->ts2secs;
@@ -2143,6 +2219,48 @@ void tracecmd_set_ts2secs(struct tracecmd_input *handle,
 	handle->use_trace_clock = false;
 }
 
+static int tsync_offset_cmp(const void *a, const void *b)
+{
+	struct ts_offset_sample *ts_a = (struct ts_offset_sample *)a;
+	struct ts_offset_sample *ts_b = (struct ts_offset_sample *)b;
+
+	if (ts_a->time > ts_b->time)
+		return 1;
+	if (ts_a->time < ts_b->time)
+		return -1;
+	return 0;
+}
+
+static void tsync_offset_load(struct tracecmd_input *handle, char *buf)
+{
+	struct host_trace_info *host = &handle->host;
+	long long *buf8 = (long long *)buf;
+	int i, j;
+
+	for (i = 0; i < host->ts_samples_count; i++) {
+		host->ts_samples[i].time = tep_read_number(handle->pevent,
+							   buf8 + i, 8);
+		host->ts_samples[i].offset = tep_read_number(handle->pevent,
+						buf8 + host->ts_samples_count+i, 8);
+	}
+	qsort(host->ts_samples, host->ts_samples_count,
+	      sizeof(struct ts_offset_sample), tsync_offset_cmp);
+	/* Filter possible samples with equal time */
+	for (i = 0, j = 0; i < host->ts_samples_count; i++) {
+		if (i == 0 || host->ts_samples[i].time != host->ts_samples[i-1].time)
+			host->ts_samples[j++] = host->ts_samples[i];
+	}
+	host->ts_samples_count = j;
+	if (j)
+		host->sync_enable = true;
+}
+
+static void trace_tsync_offset_free(struct host_trace_info *host)
+{
+	free(host->ts_samples);
+	host->ts_samples = NULL;
+}
+
 static int trace_pid_map_cmp(const void *a, const void *b)
 {
 	struct tracecmd_proc_addr_map *m_a = (struct tracecmd_proc_addr_map *)a;
@@ -2323,6 +2441,7 @@ static int handle_options(struct tracecmd_input *handle)
 	struct input_buffer_instance *buffer;
 	struct hook_list *hook;
 	char *buf;
+	int samples_size;
 	int cpus;
 
 	/* By default, use usecs, unless told otherwise */
@@ -2370,6 +2489,28 @@ static int handle_options(struct tracecmd_input *handle)
 			offset = strtoll(buf, NULL, 0);
 			handle->ts_offset += offset;
 			break;
+		case TRACECMD_OPTION_TIME_SHIFT:
+			/*
+			 * long long int (8 bytes) trace session ID
+			 * int (4 bytes) count of timestamp offsets.
+			 * long long array of size [count] of times,
+			 *      when the offsets were calculated.
+			 * long long array of size [count] of timestamp offsets.
+			 */
+			if (size < 12 || handle->flags & TRACECMD_FL_IGNORE_DATE)
+				break;
+			handle->host.trace_id = tep_read_number(handle->pevent,
+								buf, 8);
+			handle->host.ts_samples_count = tep_read_number(handle->pevent,
+									buf + 8, 4);
+			samples_size = (8 * handle->host.ts_samples_count);
+			if (size != (12 + (2 * samples_size)))
+				break;
+			handle->host.ts_samples = malloc(2 * samples_size);
+			if (!handle->host.ts_samples)
+				return -ENOMEM;
+			tsync_offset_load(handle, buf + 12);
+			break;
 		case TRACECMD_OPTION_CPUSTAT:
 			buf[size-1] = '\n';
 			cpustats = realloc(cpustats, cpustats_size + size + 1);
@@ -3078,6 +3219,8 @@ void tracecmd_close(struct tracecmd_input *handle)
 	trace_pid_map_free(handle->pid_maps);
 	handle->pid_maps = NULL;
 
+	trace_tsync_offset_free(&handle->host);
+
 	if (handle->flags & TRACECMD_FL_BUFFER_INSTANCE)
 		tracecmd_close(handle->parent);
 	else {
@@ -3532,3 +3675,38 @@ unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
 {
 	return handle->trace_id;
 }
+
+/**
+ * tracecmd_get_tsync_peer - get the trace session id of the peer host
+ * @handle: input handle for the trace.dat file
+ *
+ * Returns the trace id of the peer host, written in the trace file
+ *
+ * This information is stored in guest trace.dat file
+ */
+unsigned long long tracecmd_get_tsync_peer(struct tracecmd_input *handle)
+{
+	return handle->host.trace_id;
+}
+
+/**
+ * tracecmd_enable_tsync - enable / disable the timestamps correction
+ * @handle: input handle for the trace.dat file
+ * @enable: enable / disable the timestamps correction
+ *
+ * Enables or disables timestamps correction on file load, using the array of
+ * recorded time offsets. If "enable" is true, but there are no time offsets,
+ * function fails and -1 is returned.
+ *
+ * Returns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_enable_tsync(struct tracecmd_input *handle, bool enable)
+{
+	if (enable &&
+	    (!handle->host.ts_samples || !handle->host.ts_samples_count))
+		return -1;
+
+	handle->host.sync_enable = enable;
+
+	return 0;
+}
-- 
2.23.0

[PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file

[Tzvetomir Stoyanov (VMware)]

New trace.dat option is introduced: TRACECMD_OPTION_GUEST.
Written in the host's trace.dat file, it contains information about
guests, traced at the same time: guest trace ID, number of VCPUs and
PIDs of the host tasks, running those VCPU. The data is stored in
the file as NULL terminated string:
	"Guest %s %llu %d\n" -> guest name, number of VCPUs
	"%d %d\n" -> VCPU, PID of host task
	.....
	"%d %d\n" -> VCPU, PID of host task

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h |   5 ++
 lib/trace-cmd/trace-input.c   | 110 ++++++++++++++++++++++++++++++++++
 tracecmd/trace-record.c       |  46 ++++++++++++++
 3 files changed, 161 insertions(+)

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index b06a0c3..da8eeaf 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -88,6 +88,7 @@ enum {
 	TRACECMD_OPTION_PROCMAPS,
 	TRACECMD_OPTION_TRACEID,
 	TRACECMD_OPTION_TIME_SHIFT,
+	TRACECMD_OPTION_GUEST,
 };
 
 enum {
@@ -131,6 +132,10 @@ void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
 void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
 unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
 unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
+int tracecmd_get_guest_cpumap(struct tracecmd_input *handle,
+			      unsigned long long trace_id,
+			      char **name,
+			      int *vcpu_count, int **cpu_pid);
 unsigned long long tracecmd_get_tsync_peer(struct tracecmd_input *handle);
 int tracecmd_enable_tsync(struct tracecmd_input *handle, bool enable);
 
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index e8db876..6c4fc03 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -79,6 +79,14 @@ struct ts_offset_sample {
 	long long	offset;
 };
 
+struct guest_trace_info {
+	struct guest_trace_info	*next;
+	char			*name;
+	unsigned long long	trace_id;
+	int			vcpu_count;
+	int			*cpu_pid;
+};
+
 struct host_trace_info {
 	bool			sync_enable;
 	unsigned long long	trace_id;
@@ -112,6 +120,7 @@ struct tracecmd_input {
 	char *			trace_clock;
 	struct input_buffer_instance	*buffers;
 	int			parsing_failures;
+	struct guest_trace_info	*guest;
 
 	struct tracecmd_ftrace	finfo;
 
@@ -2297,6 +2306,67 @@ static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
 	return -1;
 }
 
+static void trace_guests_free(struct tracecmd_input *handle)
+{
+	struct guest_trace_info *guest;
+
+	while (handle->guest) {
+		guest = handle->guest;
+		handle->guest = handle->guest->next;
+		free(guest->name);
+		free(guest->cpu_pid);
+		free(guest);
+	}
+}
+
+static int trace_guest_load(struct tracecmd_input *handle, char *buf)
+{
+	struct guest_trace_info *guest = NULL;
+	unsigned long long tid;
+	char *next = NULL;
+	int cpu, pid;
+	char *line;
+
+	line = strtok_r(buf, "\n", &next);
+	if (!line)
+		goto error;
+
+	guest = calloc(1, sizeof(struct guest_trace_info));
+	if (!guest)
+		goto error;
+
+	if (sscanf(line, "%*s %ms %llu %d", &guest->name, &tid, &cpu) != 3)
+		goto error;
+	guest->trace_id = tid;
+	guest->vcpu_count = cpu;
+
+	guest->cpu_pid = calloc(guest->vcpu_count, sizeof(int));
+	if (!guest->cpu_pid)
+		goto error;
+
+	line = strtok_r(NULL, "\n", &next);
+	while (line) {
+		if (sscanf(line, "%d %d", &cpu, &pid) != 2)
+			goto error;
+
+		if (cpu < guest->vcpu_count)
+			guest->cpu_pid[cpu] = pid;
+		line = strtok_r(NULL, "\n", &next);
+	}
+
+	guest->next = handle->guest;
+	handle->guest = guest;
+	return 0;
+
+error:
+	if (guest) {
+		free(guest->cpu_pid);
+		free(guest->name);
+		free(guest);
+	}
+	return -1;
+}
+
 #define STR_PROCMAP_LINE_MAX	(PATH_MAX+22)
 static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
 {
@@ -2561,6 +2631,10 @@ static int handle_options(struct tracecmd_input *handle)
 			if (buf[size-1] == '\0')
 				trace_traceid_load(handle, buf);
 			break;
+		case TRACECMD_OPTION_GUEST:
+			if (buf[size-1] == '\0')
+				trace_guest_load(handle, buf);
+			break;
 		default:
 			warning("unknown option %d", option);
 			break;
@@ -3220,6 +3294,7 @@ void tracecmd_close(struct tracecmd_input *handle)
 	handle->pid_maps = NULL;
 
 	trace_tsync_offset_free(&handle->host);
+	trace_guests_free(handle);
 
 	if (handle->flags & TRACECMD_FL_BUFFER_INSTANCE)
 		tracecmd_close(handle->parent);
@@ -3676,6 +3751,41 @@ unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
 	return handle->trace_id;
 }
 
+/**
+ * tracecmd_get_guest_cpumap - get the mapping of guest VCPU to host process
+ * @handle: input handle for the trace.dat file
+ * @trace_id: ID of the guest tracing session
+ * @name: return, name of the guest
+ * @vcpu_count: return, number of VPUs
+ * @cpu_pid: return, array with guest VCPU to host process mapping
+ *
+ * Returns @name of the guest, number of VPUs (@vcpu_count)
+ * and array @cpu_pid with size @vcpu_count. Array index is VCPU id, array
+ * content is PID of the host process, running this VCPU.
+ *
+ * This information is stored in host trace.dat file
+ */
+int tracecmd_get_guest_cpumap(struct tracecmd_input *handle,
+			      unsigned long long trace_id,
+			      char **name,
+			      int *vcpu_count, int **cpu_pid)
+{
+	struct guest_trace_info	*guest = handle->guest;
+
+	while (guest) {
+		if (guest->trace_id == trace_id)
+			break;
+		guest = guest->next;
+	}
+	if (!guest)
+		return -1;
+
+	*name = guest->name;
+	*vcpu_count = guest->vcpu_count;
+	*cpu_pid = guest->cpu_pid;
+	return 0;
+}
+
 /**
  * tracecmd_get_tsync_peer - get the trace session id of the peer host
  * @handle: input handle for the trace.dat file
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 4bd9b7a..e4e2d63 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2884,6 +2884,19 @@ struct guest {
 static struct guest *guests;
 static size_t guests_len;
 
+static struct guest *get_guest_info(unsigned int guest_cid)
+{
+	int i;
+
+	if (!guests)
+		return NULL;
+
+	for (i = 0; i < guests_len; i++)
+		if (guest_cid == guests[i].cid)
+			return guests + i;
+	return NULL;
+}
+
 static char *get_qemu_guest_name(char *arg)
 {
 	char *tok, *end = arg;
@@ -3689,6 +3702,34 @@ static void append_buffer(struct tracecmd_output *handle,
 }
 
 
+static void
+add_guest_info(struct tracecmd_output *handle, struct buffer_instance *instance)
+{
+	struct guest *guest = get_guest_info(instance->cid);
+	struct trace_seq s;
+	int i;
+
+	if (!guest)
+		return;
+	for (i = 0; i < VCPUS_MAX; i++)
+		if (!guest->cpu_pid[i])
+			break;
+
+	trace_seq_init(&s);
+
+	trace_seq_printf(&s, "Guest %s %llu %d\n",
+			 guest->name, instance->trace_id, i);
+	for (i = 0; i < VCPUS_MAX; i++) {
+		if (!guest->cpu_pid[i])
+			break;
+		trace_seq_printf(&s, "%d %d\n", i, guest->cpu_pid[i]);
+	}
+	trace_seq_terminate(&s);
+	tracecmd_add_option(handle, TRACECMD_OPTION_GUEST,
+			    s.len + 1, s.buffer);
+	trace_seq_destroy(&s);
+}
+
 static void
 add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
 {
@@ -3975,6 +4016,11 @@ static void record_data(struct common_record_context *ctx)
 			add_pid_maps(handle, instance);
 		}
 
+		for_all_instances(instance) {
+			if (is_guest(instance))
+				add_guest_info(handle, instance);
+		}
+
 		tracecmd_append_cpu_data(handle, local_cpu_count, temp_files);
 
 		for (i = 0; i < max_cpu_count; i++)
-- 
2.23.0

[PATCH v18 14/18] trace-cmd: Add host trace clock as guest trace argument

[Tzvetomir Stoyanov (VMware)]

When tracing host and guest machines, both should use the same
tracing clock for event timestamps. If a clock is specified
as host tracing argument, with option "-C clock_name", the same
is injected as guest tracing argument. If the user wants to use
different tracing clocks, it can specify it using "-C clock_name"
as guest tracing argument. In that case, the one specified by
the user has higher priority.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/include/trace-local.h |  1 +
 tracecmd/trace-record.c        | 24 ++++++++++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 90933cc..4c8d6cb 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -165,6 +165,7 @@ enum buffer_instance_flags {
 	BUFFER_FL_PROFILE	= 1 << 1,
 	BUFFER_FL_GUEST		= 1 << 2,
 	BUFFER_FL_AGENT		= 1 << 3,
+	BUFFER_FL_HAS_CLOCK	= 1 << 4,
 };
 
 struct func_list {
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index e4e2d63..51b40ff 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -5405,6 +5405,8 @@ static void parse_record_options(int argc,
 	char *sav;
 	int name_counter = 0;
 	int neg_event = 0;
+	struct buffer_instance *instance;
+	bool guest_sync_set = false;
 
 	init_common_record_context(ctx, curr_cmd);
 
@@ -5448,6 +5450,8 @@ static void parse_record_options(int argc,
 		 */
 		if (c != 'B' && c != 'A' && is_guest(ctx->instance)) {
 			add_arg(ctx->instance, c, opts, long_options, optarg);
+			if (c == 'C')
+				ctx->instance->flags |= BUFFER_FL_HAS_CLOCK;
 			continue;
 		}
 
@@ -5562,6 +5566,9 @@ static void parse_record_options(int argc,
 			break;
 		case 'C':
 			tracecmd_alloc_instance_clock(ctx->instance->ftrace, optarg);
+			ctx->instance->flags |= BUFFER_FL_HAS_CLOCK;
+			if (is_top_instance(ctx->instance))
+				guest_sync_set = true;
 			break;
 		case 'v':
 			neg_event = 1;
@@ -5779,14 +5786,27 @@ static void parse_record_options(int argc,
 
 	/* If --date is specified, prepend it to all guest VM flags */
 	if (ctx->date) {
-		struct buffer_instance *instance;
-
 		for_all_instances(instance) {
 			if (is_guest(instance))
 				add_argv(instance, "--date", true);
 		}
 	}
 
+	if (guest_sync_set) {
+		/* If -C is specified, prepend clock to all guest VM flags */
+		for_all_instances(instance) {
+			if (tracecmd_get_instance_clock(top_instance.ftrace)) {
+				if (is_guest(instance) &&
+				    !(instance->flags & BUFFER_FL_HAS_CLOCK)) {
+					add_argv(instance,
+						 tracecmd_get_instance_clock(top_instance.ftrace),
+						 true);
+					add_argv(instance, "-C", true);
+				}
+			}
+		}
+	}
+
 	if (!ctx->filtered && ctx->instance->filter_mod)
 		add_func(&ctx->instance->filter_funcs,
 			 ctx->instance->filter_mod, "*");
-- 
2.23.0

[PATCH v18 15/18] trace-cmd: Refactor few trace-cmd internal functions.

[Tzvetomir Stoyanov (VMware)]

In order to reuse code inside trace-cmd application context,
few functions are made non static and "trace_" is prepended
to their names:
	int trace_make_vsock(unsigned int port);
	int trace_get_vsock_port(int sd, unsigned int *port);
	int trace_open_vsock(unsigned int cid, unsigned int port);
	char *trace_get_guest_file(const char *file, const char *guest);

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/include/trace-local.h |  8 ++++++++
 tracecmd/trace-agent.c         | 10 +++++-----
 tracecmd/trace-record.c        | 16 ++++++++--------
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 4c8d6cb..d3e96c2 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -19,6 +19,8 @@
 #define GUEST_FIFO_FMT		GUEST_DIR_FMT "/" GUEST_PIPE_NAME "%d"
 #define VIRTIO_FIFO_FMT		"/dev/virtio-ports/" GUEST_PIPE_NAME "%d"
 
+#define TRACE_FILENAME		"trace.dat"
+
 /* fix stupid glib guint64 typecasts and printf formats */
 typedef unsigned long long u64;
 
@@ -260,6 +262,12 @@ void tracecmd_disable_tracing(void);
 void tracecmd_enable_tracing(void);
 void tracecmd_stat_cpu(struct trace_seq *s, int cpu);
 
+int trace_make_vsock(unsigned int port);
+int trace_get_vsock_port(int sd, unsigned int *port);
+int trace_open_vsock(unsigned int cid, unsigned int port);
+
+char *trace_get_guest_file(const char *file, const char *guest);
+
 /* No longer in event-utils.h */
 void __noreturn die(const char *fmt, ...); /* Can be overriden */
 void *malloc_or_die(unsigned int size); /* Can be overridden */
diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c
index cc330b7..db58064 100644
--- a/tracecmd/trace-agent.c
+++ b/tracecmd/trace-agent.c
@@ -40,7 +40,7 @@ static int get_local_cid(unsigned int *cid)
 	return ret;
 }
 
-static int make_vsock(unsigned int port)
+int trace_make_vsock(unsigned int port)
 {
 	struct sockaddr_vm addr = {
 		.svm_family = AF_VSOCK,
@@ -64,7 +64,7 @@ static int make_vsock(unsigned int port)
 	return sd;
 }
 
-static int get_vsock_port(int sd, unsigned int *port)
+int trace_get_vsock_port(int sd, unsigned int *port)
 {
 	struct sockaddr_vm addr;
 	socklen_t addr_len = sizeof(addr);
@@ -87,11 +87,11 @@ static void make_vsocks(int nr, int *fds, unsigned int *ports)
 	int i, fd, ret;
 
 	for (i = 0; i < nr; i++) {
-		fd = make_vsock(VMADDR_PORT_ANY);
+		fd = trace_make_vsock(VMADDR_PORT_ANY);
 		if (fd < 0)
 			die("Failed to open vsocket");
 
-		ret = get_vsock_port(fd, &port);
+		ret = trace_get_vsock_port(fd, &port);
 		if (ret < 0)
 			die("Failed to get vsocket address");
 
@@ -208,7 +208,7 @@ static void agent_serve(unsigned int port)
 	nr_cpus = tracecmd_count_cpus();
 	page_size = getpagesize();
 
-	sd = make_vsock(port);
+	sd = trace_make_vsock(port);
 	if (sd < 0)
 		die("Failed to open vsocket");
 
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 51b40ff..e84b714 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -68,7 +68,7 @@ static int rt_prio;
 
 static int keep;
 
-static const char *output_file = "trace.dat";
+static const char *output_file = TRACE_FILENAME;
 
 static int latency;
 static int sleep_time = 1000;
@@ -536,7 +536,7 @@ static char *get_temp_file(struct buffer_instance *instance, int cpu)
 	return file;
 }
 
-static char *get_guest_file(const char *file, const char *guest)
+char *trace_get_guest_file(const char *file, const char *guest)
 {
 	const char *p;
 	char *out = NULL;
@@ -2772,7 +2772,7 @@ static int connect_port(const char *host, unsigned int port)
 }
 
 #ifdef VSOCK
-static int open_vsock(unsigned int cid, unsigned int port)
+int trace_open_vsock(unsigned int cid, unsigned int port)
 {
 	struct sockaddr_vm addr = {
 		.svm_family = AF_VSOCK,
@@ -2835,7 +2835,7 @@ static bool can_splice_read_vsock(void)
 }
 
 #else
-static inline int open_vsock(unsigned int cid, unsigned int port)
+int trace_open_vsock(unsigned int cid, unsigned int port)
 {
 	die("vsock is not supported");
 	return -1;
@@ -3117,7 +3117,7 @@ create_recorder_instance(struct buffer_instance *instance, const char *file, int
 		if (instance->use_fifos)
 			fd = instance->fds[cpu];
 		else
-			fd = open_vsock(instance->cid, instance->client_ports[cpu]);
+			fd = trace_open_vsock(instance->cid, instance->client_ports[cpu]);
 		if (fd < 0)
 			die("Failed to connect to agent");
 
@@ -3508,7 +3508,7 @@ static void connect_to_agent(struct buffer_instance *instance)
 		use_fifos = nr_fifos > 0;
 	}
 
-	sd = open_vsock(instance->cid, instance->port);
+	sd = trace_open_vsock(instance->cid, instance->port);
 	if (sd < 0)
 		die("Failed to connect to vsocket @%u:%u",
 		    instance->cid, instance->port);
@@ -3562,7 +3562,7 @@ static void setup_guest(struct buffer_instance *instance)
 	int fd;
 
 	/* Create a place to store the guest meta data */
-	file = get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
+	file = trace_get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
 	if (!file)
 		die("Failed to allocate memory");
 
@@ -3887,7 +3887,7 @@ static void write_guest_file(struct buffer_instance *instance)
 	char **temp_files;
 	int i, fd;
 
-	file = get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
+	file = trace_get_guest_file(output_file, tracecmd_get_instance_name(instance->ftrace));
 	if (!file)
 		die("Failed to allocate memory");
 
-- 
2.23.0

[PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization

[Tzvetomir Stoyanov (VMware)]

The infrastructure for host - guest timestamp synchronization is divided
in two parts:
 - logic in libtracecmd
 - logic in trace-cmd application

The libtracecmd is extended with new trace message, MSG_TIME_SYNC, used to
exchange time synch information between host and guest. The trace request and
response messages are extended to handle the time synch negotiation. The logic
is implemented in trace-timesync.c file:
 - Register / unregister time sync protocols.
 - Choosing what protocol will be used for a tracing session.
 - Init common context, used by all protocols - a ftrace instance, vsockets.
 - Invoke protocol routines to perform time synchronization.
 - Store calculated offsets in an array.

The trace-cmd application is extended to perform timestamp synchronization.
The main logic is in trace-tsync.c file
 - Negotiate what time synch algorithm will be used for the tracing session.
 - Run pthreads, to do continuous timestamp synchronization, during the trace.
 - Store calculated offsets in guest's trace.dat file, using TRACECMD_OPTION_TIME_SHIFT option
 - A new trace-cmd option is added, to control the timestamp synchronization:
      --tsync-interval: set the time sync loop interval, in ms. The default
   value is 0 - timestamp synchronization is performed twice, before and after
   the trace. If a negative number is specified, the timestamp synchronization
   is disabled.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 Documentation/trace-cmd-record.1.txt      |   7 +
 include/trace-cmd/trace-cmd.h             |  59 ++-
 lib/trace-cmd/Makefile                    |   1 +
 lib/trace-cmd/include/trace-tsync-local.h |  38 ++
 lib/trace-cmd/trace-msg.c                 | 394 ++++++++++++++---
 lib/trace-cmd/trace-timesync.c            | 496 ++++++++++++++++++++++
 tracecmd/Makefile                         |   3 +-
 tracecmd/include/trace-local.h            |  11 +
 tracecmd/trace-agent.c                    |  38 +-
 tracecmd/trace-record.c                   |  42 +-
 tracecmd/trace-tsync.c                    | 271 ++++++++++++
 tracecmd/trace-usage.c                    |   4 +
 12 files changed, 1297 insertions(+), 67 deletions(-)
 create mode 100644 lib/trace-cmd/include/trace-tsync-local.h
 create mode 100644 lib/trace-cmd/trace-timesync.c
 create mode 100644 tracecmd/trace-tsync.c

diff --git a/Documentation/trace-cmd-record.1.txt b/Documentation/trace-cmd-record.1.txt
index 0d75e43..f5ecad5 100644
--- a/Documentation/trace-cmd-record.1.txt
+++ b/Documentation/trace-cmd-record.1.txt
@@ -338,6 +338,13 @@ OPTIONS
     the offset will also be in nanoseconds even if the displayed units are
     in microseconds.
 
+*--tsync-interval*::
+    Set the loop interval, in ms, for timestamps synchronization with guests:
+        If a negative number is specified, timestamps synchronization is disabled
+        If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
+        at the beginning and at the end of the trace.
+        Timestamps synchronization with guests works only if there is support for VSOCK.\n"
+
 *--stderr*::
     Have output go to stderr instead of stdout, but the output of the command
     executed will not be changed. This is useful if you want to monitor the
diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index da8eeaf..bf52785 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -362,19 +362,38 @@ void tracecmd_msg_set_done(struct tracecmd_msg_handle *msg_handle);
 
 int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
 				int argc, char **argv, bool use_fifos,
-				unsigned long long trace_id);
+				unsigned long long trace_id,
+				char *tsync_protos,
+				int tsync_protos_size);
+
 int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
 				int *argc, char ***argv, bool *use_fifos,
-				unsigned long long *trace_id);
+				unsigned long long *trace_id,
+				char **tsync_protos,
+				unsigned int *tsync_protos_size);
 
 int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int nr_cpus, int page_size,
 				 unsigned int *ports, bool use_fifos,
-				 unsigned long long trace_id);
+				 unsigned long long trace_id,
+				 unsigned int tsync_proto,
+				 unsigned int tsync_port);
 int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int *nr_cpus, int *page_size,
 				 unsigned int **ports, bool *use_fifos,
-				 unsigned long long *trace_id);
+				 unsigned long long *trace_id,
+				 unsigned int *tsync_proto,
+				 unsigned int *tsync_port);
+
+int tracecmd_msg_send_time_sync(struct tracecmd_msg_handle *msg_handle,
+				unsigned int sync_protocol,
+				unsigned int sync_msg_id,
+				unsigned int payload_size, char *payload);
+int tracecmd_msg_recv_time_sync(struct tracecmd_msg_handle *msg_handle,
+				unsigned int *sync_protocol,
+				unsigned int *sync_msg_id,
+				unsigned int *payload_size, char **payload);
+
 /* --- ftrace instances --- */
 
 struct tracecmd_instance;
@@ -407,6 +426,38 @@ int tracecmd_iterate_raw_events(struct tep_handle *tep,
 				void *callback_context);
 
 
+/* --- Timestamp synchronization --- */
+
+enum{
+	TRACECMD_TIME_SYNC_PROTO_NONE	= 0,
+};
+enum{
+	TRACECMD_TIME_SYNC_CMD_PROBE	= 1,
+	TRACECMD_TIME_SYNC_CMD_STOP	= 2,
+};
+
+#define TRACECMD_TIME_SYNC_PROTO_PTP_WEIGHT	10
+
+struct tracecmd_time_sync {
+	unsigned int			sync_proto;
+	int				loop_interval;
+	pthread_mutex_t			lock;
+	pthread_cond_t			cond;
+	char				*clock_str;
+	struct tracecmd_msg_handle	*msg_handle;
+	void				*context;
+};
+
+void tracecmd_tsync_init(void);
+int tracecmd_tsync_proto_getall(char **proto_mask, int *words);
+unsigned int tracecmd_tsync_proto_select(char *proto_mask, int words);
+bool tsync_proto_is_supported(unsigned int proto_id);
+void tracecmd_tsync_with_host(struct tracecmd_time_sync *tsync);
+void tracecmd_tsync_with_guest(struct tracecmd_time_sync *tsync);
+int tracecmd_tsync_get_offsets(struct tracecmd_time_sync *tsync,
+				int *count,
+				long long **ts, long long **offsets);
+void tracecmd_tsync_free(struct tracecmd_time_sync *tsync);
 
 /* --- Plugin handling --- */
 extern struct tep_plugin_option trace_ftrace_options[];
diff --git a/lib/trace-cmd/Makefile b/lib/trace-cmd/Makefile
index 18c7013..6221b36 100644
--- a/lib/trace-cmd/Makefile
+++ b/lib/trace-cmd/Makefile
@@ -16,6 +16,7 @@ OBJS += trace-util.o
 OBJS += trace-instance.o
 OBJS += trace-filter-hash.o
 OBJS += trace-msg.o
+OBJS += trace-timesync.o
 
 # Additional util objects
 OBJS += trace-blk-hack.o
diff --git a/lib/trace-cmd/include/trace-tsync-local.h b/lib/trace-cmd/include/trace-tsync-local.h
new file mode 100644
index 0000000..511c838
--- /dev/null
+++ b/lib/trace-cmd/include/trace-tsync-local.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: LGPL-2.1 */
+/*
+ * Copyright (C) 2019, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ *
+ */
+#ifndef _TRACE_TSYNC_LOCAL_H
+#define _TRACE_TSYNC_LOCAL_H
+
+#include <stdbool.h>
+
+struct clock_sync_context {
+	void				*proto_data;	/* time sync protocol specific data */
+	bool				server;		/* server or guest time sync role */
+	struct tracecmd_instance	*vinst;		/* ftrace buffer, used for time sync events */
+
+	/* Arrays with calculated time offsets at given time */
+	int				sync_size;	/* Allocated size of sync_ts and sync_offsets */
+	int				sync_count;	/* Number of elements in sync_ts and sync_offsets */
+	long long			*sync_ts;
+	long long			*sync_offsets;
+
+	/* Identifiers of local and remote time sync peers: cid and port */
+	unsigned int			local_cid;
+	unsigned int			local_port;
+	unsigned int			remote_cid;
+	unsigned int			remote_port;
+};
+
+int tracecmd_tsync_proto_register(unsigned int proto_id, int weight,
+				int (*init)(struct tracecmd_time_sync *),
+				int (*free)(struct tracecmd_time_sync *),
+				int (*calc)(struct tracecmd_time_sync *,
+					    long long *, long long *));
+int tracecmd_tsync_proto_unregister(unsigned int proto_id);
+
+int ptp_clock_sync_register(void);
+
+#endif /* _TRACE_TSYNC_LOCAL_H */
diff --git a/lib/trace-cmd/trace-msg.c b/lib/trace-cmd/trace-msg.c
index a34297f..551b9a0 100644
--- a/lib/trace-cmd/trace-msg.c
+++ b/lib/trace-cmd/trace-msg.c
@@ -28,6 +28,8 @@
 
 typedef __u32 u32;
 typedef __be32 be32;
+typedef __u64 u64;
+typedef __s64 s64;
 
 static inline void dprint(const char *fmt, ...)
 {
@@ -60,9 +62,20 @@ struct tracecmd_msg_rinit {
 	be32 cpus;
 } __attribute__((packed));
 
+#define TRACE_REQ_PARAM_SIZE  (2 * sizeof(int))
+enum trace_req_params {
+	TRACE_REQUEST_ARGS,
+	TRACE_REQUEST_TSYNC_PROTOS,
+};
+
+struct tracecmd_msg_trace_req_param {
+	int id;
+	int length;
+	char *value;
+};
+
 struct tracecmd_msg_trace_req {
 	be32 flags;
-	be32 argc;
 	u64 trace_id;
 } __attribute__((packed));
 
@@ -71,6 +84,13 @@ struct tracecmd_msg_trace_resp {
 	be32 cpus;
 	be32 page_size;
 	u64 trace_id;
+	be32 tsync_proto;
+	be32 tsync_port;
+} __attribute__((packed));
+
+struct tracecmd_msg_tsync {
+	be32 sync_protocol;
+	be32 sync_msg_id;
 } __attribute__((packed));
 
 struct tracecmd_msg_header {
@@ -88,7 +108,8 @@ struct tracecmd_msg_header {
 	C(NOT_SUPP,	5,	0),					\
 	C(TRACE_REQ,	6,	sizeof(struct tracecmd_msg_trace_req)),	\
 	C(TRACE_RESP,	7,	sizeof(struct tracecmd_msg_trace_resp)),\
-	C(CLOSE_RESP,	8,	0),
+	C(CLOSE_RESP,	8,	0),					\
+	C(TIME_SYNC,	9,	sizeof(struct tracecmd_msg_tsync)),
 
 #undef C
 #define C(a,b,c)	MSG_##a = b
@@ -122,6 +143,7 @@ struct tracecmd_msg {
 		struct tracecmd_msg_rinit	rinit;
 		struct tracecmd_msg_trace_req	trace_req;
 		struct tracecmd_msg_trace_resp	trace_resp;
+		struct tracecmd_msg_tsync	tsync;
 	};
 	char					*buf;
 } __attribute__((packed));
@@ -264,6 +286,17 @@ static int tracecmd_msg_send(int fd, struct tracecmd_msg *msg)
 	return ret;
 }
 
+static int msg_send_nofree(int fd, struct tracecmd_msg *msg)
+{
+	int ret = 0;
+
+	ret = msg_write(fd, msg);
+	if (ret < 0)
+		ret = -ECOMM;
+
+	return ret;
+}
+
 static int msg_read(int fd, void *buf, u32 size, int *n)
 {
 	ssize_t r;
@@ -813,82 +846,142 @@ int tracecmd_msg_wait_close_resp(struct tracecmd_msg_handle *msg_handle)
 	return tracecmd_msg_wait_for_cmd(msg_handle, MSG_CLOSE_RESP);
 }
 
-static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv,
-			  bool use_fifos, unsigned long long trace_id)
+static int make_trace_req_protos(char **buf, int *size,
+				 int protos_size, char *tsync_protos)
+{
+	size_t buf_size = 0;
+	char *nbuf;
+	char *p;
+
+	buf_size = TRACE_REQ_PARAM_SIZE + protos_size;
+	nbuf = realloc(*buf, *size + buf_size);
+	if (!nbuf)
+		return -1;
+
+	p = nbuf + *size;
+	memset(p, 0, buf_size);
+
+	*(unsigned int *)p = htonl(TRACE_REQUEST_TSYNC_PROTOS);
+	p += sizeof(int);
+	*(unsigned int *)p = htonl(protos_size);
+	p += sizeof(int);
+
+	memcpy(p, tsync_protos, protos_size);
+
+	*size += buf_size;
+	*buf = nbuf;
+	return 0;
+}
+
+static int make_trace_req_args(char **buf, int *size, int argc, char **argv)
 {
 	size_t args_size = 0;
+	size_t buf_size = 0;
+	char *nbuf;
 	char *p;
 	int i;
 
+	args_size = sizeof(int);
 	for (i = 0; i < argc; i++)
 		args_size += strlen(argv[i]) + 1;
 
-	msg->hdr.size = htonl(ntohl(msg->hdr.size) + args_size);
-	msg->trace_req.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
-	msg->trace_req.argc = htonl(argc);
-	msg->trace_req.trace_id = htonll(trace_id);
-	msg->buf = calloc(args_size, 1);
-	if (!msg->buf)
-		return -ENOMEM;
+	buf_size = TRACE_REQ_PARAM_SIZE + args_size;
+	nbuf = realloc(*buf, *size + buf_size);
+	if (!nbuf)
+		return -1;
+
+	p = nbuf + *size;
+	memset(p, 0, buf_size);
+
+	*(unsigned int *)p = htonl(TRACE_REQUEST_ARGS);
+	p += sizeof(int);
+	*(unsigned int *)p = htonl(args_size);
+	p += sizeof(int);
 
-	p = msg->buf;
+	*(unsigned int *)p = htonl(argc);
+	p += sizeof(int);
 	for (i = 0; i < argc; i++)
 		p = stpcpy(p, argv[i]) + 1;
 
+	*size += buf_size;
+	*buf = nbuf;
+	return 0;
+}
+
+static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv,
+			  bool use_fifos, unsigned long long trace_id,
+			  char *tsync_protos, int tsync_protos_size)
+{
+	int size = 0;
+	char *buf = NULL;
+
+	msg->trace_req.flags = 0;
+	if (use_fifos)
+		msg->trace_req.flags |= MSG_TRACE_USE_FIFOS;
+	msg->trace_req.flags = htonl(msg->trace_req.flags);
+	msg->trace_req.trace_id = htonll(trace_id);
+
+	if (argc && argv)
+		make_trace_req_args(&buf, &size, argc, argv);
+	if (tsync_protos_size && tsync_protos)
+		make_trace_req_protos(&buf, &size,
+				      tsync_protos_size, tsync_protos);
+
+	msg->buf = buf;
+	msg->hdr.size = htonl(ntohl(msg->hdr.size) + size);
+
 	return 0;
 }
 
 int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
 				int argc, char **argv, bool use_fifos,
-				unsigned long long trace_id)
+				unsigned long long trace_id,
+				char *tsync_protos,
+				int tsync_protos_size)
 {
 	struct tracecmd_msg msg;
 	int ret;
 
 	tracecmd_msg_init(MSG_TRACE_REQ, &msg);
 	ret = make_trace_req(&msg, argc, argv,
-			     use_fifos, trace_id);
+			     use_fifos, trace_id,
+			     tsync_protos, tsync_protos_size);
 	if (ret < 0)
 		return ret;
 
 	return tracecmd_msg_send(msg_handle->fd, &msg);
 }
 
- /*
-  * NOTE: On success, the returned `argv` should be freed with:
-  *     free(argv[0]);
-  *     free(argv);
-  */
-int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
-				int *argc, char ***argv, bool *use_fifos,
-				unsigned long long *trace_id)
+static int get_trace_req_protos(char *buf, int length,
+				char **tsync_protos,
+				unsigned int *tsync_protos_size)
 {
-	struct tracecmd_msg msg;
-	char *p, *buf_end, **args;
-	int i, ret, nr_args;
-	ssize_t buf_len;
+	*tsync_protos = malloc(length);
+	if (!*tsync_protos)
+		return -1;
+	memcpy(*tsync_protos, buf, length);
+	*tsync_protos_size = length;
 
-	ret = tracecmd_msg_recv(msg_handle->fd, &msg);
-	if (ret < 0)
-		return ret;
+	return 0;
+}
 
-	if (ntohl(msg.hdr.cmd) != MSG_TRACE_REQ) {
-		ret = -ENOTSUP;
-		goto out;
-	}
+static int get_trace_req_args(char *buf, int length, int *argc, char ***argv)
+{
+	unsigned int nr_args;
+	char *p, *buf_end;
+	char **args = NULL;
+	char *vagrs = NULL;
+	int ret;
+	int i;
 
-	nr_args = ntohl(msg.trace_req.argc);
-	if (nr_args <= 0) {
+	if (length <= sizeof(int) || buf[length - 1] != '\0') {
 		ret = -EINVAL;
 		goto out;
 	}
 
-	buf_len = ntohl(msg.hdr.size) - MSG_HDR_LEN - ntohl(msg.hdr.cmd_size);
-	buf_end = (char *)msg.buf + buf_len;
-	if (buf_len <= 0 && ((char *)msg.buf)[buf_len-1] != '\0') {
-		ret = -EINVAL;
-		goto out;
-	}
+	nr_args = ntohl(*(unsigned int *)buf);
+	buf += sizeof(int);
+	length -= sizeof(int);
 
 	args = calloc(nr_args, sizeof(*args));
 	if (!args) {
@@ -896,10 +989,18 @@ int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
 		goto out;
 	}
 
-	for (i = 0, p = msg.buf; i < nr_args; i++, p++) {
+	vagrs = calloc(length, sizeof(char));
+	if (!vagrs) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	memcpy(vagrs, buf, length);
+	buf_end = vagrs + length;
+	for (i = 0, p = vagrs; i < nr_args; i++, p++) {
 		if (p >= buf_end) {
 			ret = -EINVAL;
-			goto out_args;
+			goto out;
 		}
 		args[i] = p;
 		p = strchr(p, '\0');
@@ -907,19 +1008,83 @@ int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
 
 	*argc = nr_args;
 	*argv = args;
+	return 0;
+
+out:
+	free(args);
+	free(vagrs);
+	return ret;
+
+}
+
+/*
+ * NOTE: On success, the returned `argv` should be freed with:
+ *     free(argv[0]);
+ *     free(argv);
+ * and `tsync_protos` with free(tsync_protos);
+ */
+int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
+				int *argc, char ***argv, bool *use_fifos,
+				unsigned long long *trace_id,
+				char **tsync_protos,
+				unsigned int *tsync_protos_size)
+{
+	struct tracecmd_msg msg;
+	unsigned int param_id;
+	int param_length;
+	ssize_t buf_len;
+	char *p;
+	int ret;
+
+	ret = tracecmd_msg_recv(msg_handle->fd, &msg);
+	if (ret < 0)
+		return ret;
+
+	if (ntohl(msg.hdr.cmd) != MSG_TRACE_REQ) {
+		ret = -ENOTSUP;
+		goto out;
+	}
+
+	buf_len = ntohl(msg.hdr.size) - MSG_HDR_LEN - ntohl(msg.hdr.cmd_size);
+	if (buf_len < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	*use_fifos = ntohl(msg.trace_req.flags) & MSG_TRACE_USE_FIFOS;
 	*trace_id = ntohll(msg.trace_req.trace_id);
 
-	/*
-	 * On success we're passing msg.buf to the caller through argv[0] so we
-	 * reset it here before calling msg_free().
-	 */
-	msg.buf = NULL;
+	p = msg.buf;
+	while (buf_len > 2 * sizeof(int)) {
+		param_id = ntohl(*((unsigned int *)p));
+		p += sizeof(int);
+		buf_len -= sizeof(int);
+		param_length = ntohl(*((unsigned int *)p));
+		p += sizeof(int);
+		buf_len -= sizeof(int);
+		if (buf_len < param_length)
+			break;
+		ret = 0;
+		switch (param_id) {
+		case TRACE_REQUEST_ARGS:
+			ret = get_trace_req_args(p, param_length, argc, argv);
+			break;
+		case TRACE_REQUEST_TSYNC_PROTOS:
+			ret = get_trace_req_protos(p, param_length,
+						   tsync_protos, tsync_protos_size);
+			break;
+		default:
+			break;
+		}
+		if (ret)
+			break;
+		buf_len -= param_length;
+		p += param_length;
+	}
+
 	msg_free(&msg);
 	return 0;
 
-out_args:
-	free(args);
 out:
 	error_operation(&msg);
 	if (ret == -EOPNOTSUPP)
@@ -928,9 +1093,118 @@ out:
 	return ret;
 }
 
+/**
+ * tracecmd_msg_send_time_sync - Send a time sync packet
+ * @msg_handle: message handle, holding the communication context
+ * @sync_protocol: id of the time synch protocol
+ * @sync_msg_id: id if the time synch message, protocol dependent
+ * @payload_size: size of the packet payload, 0 in case of no payload
+ * @payload: pointer to the packet payload, or NULL in case of no payload
+ *
+ * Returns 0 if packet is sent successfully, or negative error otherwise.
+ */
+int tracecmd_msg_send_time_sync(struct tracecmd_msg_handle *msg_handle,
+				unsigned int sync_protocol,
+				unsigned int sync_msg_id,
+				unsigned int payload_size, char *payload)
+{
+	struct tracecmd_msg msg;
+
+	tracecmd_msg_init(MSG_TIME_SYNC, &msg);
+	msg.tsync.sync_protocol = htonl(sync_protocol);
+	msg.tsync.sync_msg_id = htonl(sync_msg_id);
+	msg.hdr.size = htonl(ntohl(msg.hdr.size) + payload_size);
+
+	msg.buf = payload;
+	return msg_send_nofree(msg_handle->fd, &msg);
+}
+
+/**
+ * tracecmd_msg_recv_time_sync - Receive a time sync packet
+ * @msg_handle: message handle, holding the communication context
+ * @sync_protocol: return the id of the packet's time synch protocol
+ * @sync_msg_id: return the id of the packet's time synch message
+ * @payload_size: size of the packet's payload, can be:
+ *		 NULL - the payload is not interested and should be ignored
+ *		 pointer to int, with value 0 - update with the size of the payload
+ *						allocate memory and cpy the payload
+ *						into it
+ *		 pointer to int, with value greater than 0 - expected size of the
+ *							     payload, preallocated
+ *							     memory is passed to the API
+ *							     with that size
+ *@payload: pointer to the packet payload, can be:
+ *	     NULL - the payload is not interested and should be ignored
+ *	     pointer to char *, with value NULL - a new memory is allocated and returned
+ *						  here, containing the packet's payload
+ *						  the @payload_size is updated with the
+ *						  size of the allocated memory. It must be
+ *						  freed by free()
+ *	     pointer to char *, with no-NULL value - A prealocated array is passed, with size
+ *						     @payload_size. If payload's size is equal
+ *						     or less, it will be copied here.
+ *
+ * Returns 0 if packet is received successfully, or negative error otherwise.
+ */
+int tracecmd_msg_recv_time_sync(struct tracecmd_msg_handle *msg_handle,
+				unsigned int *sync_protocol,
+				unsigned int *sync_msg_id,
+				unsigned int *payload_size, char **payload)
+{
+	struct tracecmd_msg msg;
+	int ret = -1;
+	int buf_size;
+
+	memset(&msg, 0, sizeof(msg));
+	ret = tracecmd_msg_recv(msg_handle->fd, &msg);
+	if (ret < 0)
+		goto out;
+
+	if (ntohl(msg.hdr.cmd) != MSG_TIME_SYNC) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (sync_protocol)
+		*sync_protocol = ntohl(msg.tsync.sync_protocol);
+	if (sync_msg_id)
+		*sync_msg_id = ntohl(msg.tsync.sync_msg_id);
+
+	buf_size = msg_buf_len(&msg);
+	if (buf_size < 0) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (buf_size && payload && payload_size) {
+		if (*payload_size) {
+			if (*payload_size < buf_size || *payload == NULL) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			memcpy(*payload, msg.buf, buf_size);
+			goto out;
+		}
+
+		*payload = malloc(buf_size);
+		if (*payload == NULL) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		*payload_size = buf_size;
+		memcpy(*payload, msg.buf, buf_size);
+	}
+
+out:
+	msg_free(&msg);
+	return ret;
+}
+
 static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus,
 			   unsigned int *ports, bool use_fifos,
-			   unsigned long long trace_id)
+			   unsigned long long trace_id,
+			   unsigned int tsync_proto,
+			   unsigned int tsync_port)
 {
 	int data_size;
 
@@ -941,7 +1215,11 @@ static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus,
 	write_uints(msg->buf, data_size, ports, nr_cpus);
 
 	msg->hdr.size = htonl(ntohl(msg->hdr.size) + data_size);
-	msg->trace_resp.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
+	msg->trace_req.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
+	msg->trace_resp.flags = htonl(msg->trace_resp.flags);
+	msg->trace_resp.tsync_proto = htonl(tsync_proto);
+	msg->trace_resp.tsync_port = htonl(tsync_port);
+
 	msg->trace_resp.cpus = htonl(nr_cpus);
 	msg->trace_resp.page_size = htonl(page_size);
 	msg->trace_resp.trace_id = htonll(trace_id);
@@ -952,14 +1230,16 @@ static int make_trace_resp(struct tracecmd_msg *msg, int page_size, int nr_cpus,
 int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int nr_cpus, int page_size,
 				 unsigned int *ports, bool use_fifos,
-				 unsigned long long trace_id)
+				 unsigned long long trace_id,
+				 unsigned int tsync_proto,
+				 unsigned int tsync_port)
 {
 	struct tracecmd_msg msg;
 	int ret;
 
 	tracecmd_msg_init(MSG_TRACE_RESP, &msg);
 	ret = make_trace_resp(&msg, page_size, nr_cpus, ports,
-			      use_fifos, trace_id);
+			      use_fifos, trace_id, tsync_proto, tsync_port);
 	if (ret < 0)
 		return ret;
 
@@ -969,7 +1249,9 @@ int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
 int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 				 int *nr_cpus, int *page_size,
 				 unsigned int **ports, bool *use_fifos,
-				 unsigned long long *trace_id)
+				 unsigned long long *trace_id,
+				 unsigned int *tsync_proto,
+				 unsigned int *tsync_port)
 {
 	struct tracecmd_msg msg;
 	char *p, *buf_end;
@@ -996,6 +1278,8 @@ int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
 	*nr_cpus = ntohl(msg.trace_resp.cpus);
 	*page_size = ntohl(msg.trace_resp.page_size);
 	*trace_id = ntohll(msg.trace_resp.trace_id);
+	*tsync_proto = ntohl(msg.trace_resp.tsync_proto);
+	*tsync_port = ntohl(msg.trace_resp.tsync_port);
 	*ports = calloc(*nr_cpus, sizeof(**ports));
 	if (!*ports) {
 		ret = -ENOMEM;
diff --git a/lib/trace-cmd/trace-timesync.c b/lib/trace-cmd/trace-timesync.c
new file mode 100644
index 0000000..6f23a63
--- /dev/null
+++ b/lib/trace-cmd/trace-timesync.c
@@ -0,0 +1,496 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2019, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ *
+ */
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <linux/vm_sockets.h>
+#include <linux/limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <dirent.h>
+#include <errno.h>
+#include <pthread.h>
+
+#include "trace-cmd.h"
+#include "trace-cmd-local.h"
+#include "trace-tsync-local.h"
+
+struct tsync_proto {
+	struct tsync_proto *next;
+	unsigned int proto_id;
+	int	weight;
+
+	int (*clock_sync_init)(struct tracecmd_time_sync *clock_context);
+	int (*clock_sync_free)(struct tracecmd_time_sync *clock_context);
+	int (*clock_sync_calc)(struct tracecmd_time_sync *clock_context,
+			       long long *offset, long long *timestamp);
+};
+
+static struct tsync_proto *tsync_proto_list;
+
+static struct tsync_proto *tsync_proto_find(unsigned int proto_id)
+{
+	struct tsync_proto *proto;
+
+	for (proto = tsync_proto_list; proto; proto = proto->next)
+		if (proto->proto_id == proto_id)
+			return proto;
+
+	return NULL;
+}
+
+int tracecmd_tsync_proto_register(unsigned int proto_id, int weight,
+				int (*init)(struct tracecmd_time_sync *),
+				int (*free)(struct tracecmd_time_sync *),
+				int (*calc)(struct tracecmd_time_sync *,
+					    long long *, long long *))
+{
+	struct tsync_proto *proto;
+
+	if (tsync_proto_find(proto_id))
+		return -1;
+	proto = calloc(1, sizeof(struct tsync_proto));
+	if (!proto)
+		return -1;
+	proto->proto_id = proto_id;
+	proto->weight = weight;
+	proto->clock_sync_init = init;
+	proto->clock_sync_free = free;
+	proto->clock_sync_calc = calc;
+
+	proto->next = tsync_proto_list;
+	tsync_proto_list = proto;
+	return 0;
+}
+
+int tracecmd_tsync_proto_unregister(unsigned int proto_id)
+{
+	struct tsync_proto **last = &tsync_proto_list;
+
+	for (; *last; last = &(*last)->next) {
+		if ((*last)->proto_id == proto_id) {
+			struct tsync_proto *proto = *last;
+
+			*last = proto->next;
+			free(proto);
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+bool tsync_proto_is_supported(unsigned int proto_id)
+{
+	if (tsync_proto_find(proto_id))
+		return true;
+	return false;
+}
+
+/**
+ * tracecmd_tsync_get_offsets - Return the calculated time offsets
+ *
+ * @tsync: Pointer to time sync context
+ * @count: Returns the number of calculated time offsets
+ * @ts: Array of size @count containing timestamps of callculated offsets
+ * @offsets: array of size @count, containing offsets for each timestamp
+ *
+ * Retuns -1 in case of an error, or 0 otherwise
+ */
+int tracecmd_tsync_get_offsets(struct tracecmd_time_sync *tsync,
+				int *count,
+				long long **ts, long long **offsets)
+{
+	struct clock_sync_context *tsync_context;
+
+	if (!tsync || !tsync->context)
+		return -1;
+	tsync_context = (struct clock_sync_context *)tsync->context;
+	if (count)
+		*count = tsync_context->sync_count;
+	if (ts)
+		*ts = tsync_context->sync_ts;
+	if (offsets)
+		*offsets = tsync_context->sync_offsets;
+	return 0;
+}
+
+
+#define PROTO_MASK_SIZE (sizeof(char))
+/**
+ * tracecmd_tsync_proto_select - Select time sync protocol, to be used for
+ *		timestamp synchronization with a peer
+ *
+ * @proto_mask: bitmask array of time sync protocols, supported by the peer
+ * @words: size of the @protos array
+ *
+ * Retuns Id of a time sync protocol, that can be used with the peer, or 0
+ *	  in case there is no match with supported protocols
+ */
+unsigned int tracecmd_tsync_proto_select(char *proto_mask, int words)
+{
+	struct tsync_proto *selected = NULL;
+	struct tsync_proto *proto;
+	int word;
+	int id;
+
+	for (word = 0; word < words; word++) {
+		for (proto = tsync_proto_list; proto; proto = proto->next) {
+			if (proto->proto_id < word * PROTO_MASK_SIZE)
+				continue;
+
+			id = proto->proto_id - word * PROTO_MASK_SIZE;
+			if (id >= PROTO_MASK_SIZE)
+				continue;
+
+			if ((1 << id) & proto_mask[word]) {
+				if (selected) {
+					if (selected->weight < proto->weight)
+						selected = proto;
+				} else
+					selected = proto;
+			}
+		}
+	}
+
+	if (selected)
+		return selected->proto_id;
+
+	return 0;
+}
+
+/**
+ * tracecmd_tsync_proto_getall - Returns bitmask of all supported
+ *				 time sync protocols
+ * @proto_mask: return, allocated bitmask array of time sync protocols,
+ *	       supported by the peer. Must be freed by free()
+ * @words: return, allocated size of the @protobits array
+ *
+ * If completed successfully 0 is returned and allocated array in @proto_mask of
+ * size @words. In case of an error, -1 is returned.
+ * @proto_mask must be freed with free()
+ */
+int tracecmd_tsync_proto_getall(char **proto_mask, int *words)
+{
+	struct tsync_proto *proto;
+	int proto_max = 0;
+	int count = 0;
+	char *protos;
+
+	for (proto = tsync_proto_list; proto; proto = proto->next)
+		if (proto->proto_id > proto_max)
+			proto_max = proto->proto_id;
+
+	count = proto_max / PROTO_MASK_SIZE + 1;
+	protos = calloc(count, sizeof(char));
+	if (!protos)
+		return -1;
+
+	for (proto = tsync_proto_list; proto; proto = proto->next) {
+		if ((proto->proto_id / PROTO_MASK_SIZE) >= count)
+			continue;
+		protos[proto->proto_id / PROTO_MASK_SIZE] |=
+				(1 << (proto->proto_id % PROTO_MASK_SIZE));
+	}
+
+	*proto_mask = protos;
+	*words = count;
+	return 0;
+}
+
+static int get_vsocket_params(int fd, unsigned int *lcid, unsigned int *lport,
+			      unsigned int *rcid, unsigned int *rport)
+{
+	struct sockaddr_vm addr;
+	socklen_t addr_len = sizeof(addr);
+
+	memset(&addr, 0, sizeof(addr));
+	if (getsockname(fd, (struct sockaddr *)&addr, &addr_len))
+		return -1;
+	if (addr.svm_family != AF_VSOCK)
+		return -1;
+	*lport = addr.svm_port;
+	*lcid = addr.svm_cid;
+
+	memset(&addr, 0, sizeof(addr));
+	addr_len = sizeof(addr);
+	if (getpeername(fd, (struct sockaddr *)&addr, &addr_len))
+		return -1;
+	if (addr.svm_family != AF_VSOCK)
+		return -1;
+	*rport = addr.svm_port;
+	*rcid = addr.svm_cid;
+
+	return 0;
+}
+
+static struct tracecmd_instance *
+clock_synch_create_instance(const char *clock, unsigned int cid)
+{
+	struct tracecmd_instance *vinst;
+	char inst_name[256];
+
+	snprintf(inst_name, 256, "clock_synch-%d", cid);
+
+	vinst = tracecmd_alloc_instance(inst_name);
+	if (!vinst)
+		return NULL;
+
+	tracecmd_make_instance(vinst);
+	tracecmd_write_instance_file(vinst, "trace", "\0", NULL);
+	tracecmd_alloc_instance_clock(vinst, clock);
+	tracecmd_set_clock(vinst, NULL);
+	return vinst;
+}
+
+static void
+clock_synch_delete_instance(struct tracecmd_instance *inst)
+{
+	if (!inst)
+		return;
+	tracecmd_remove_instance(inst);
+	tracecmd_free_instance(inst);
+}
+
+static int clock_context_init(struct tracecmd_time_sync *tsync, bool server)
+{
+	struct clock_sync_context *clock = NULL;
+	struct tsync_proto *protocol;
+
+	if (tsync->context)
+		return 0;
+
+	protocol = tsync_proto_find(tsync->sync_proto);
+	if (!protocol)
+		return -1;
+
+	clock = calloc(1, sizeof(struct clock_sync_context));
+	if (!clock)
+		return -1;
+
+	clock->server = server;
+	if (get_vsocket_params(tsync->msg_handle->fd, &clock->local_cid,
+			       &clock->local_port, &clock->remote_cid,
+			       &clock->remote_port))
+		goto error;
+
+	clock->vinst = clock_synch_create_instance(tsync->clock_str,
+						   clock->remote_cid);
+	if (!clock->vinst)
+		goto error;
+
+	tsync->context = clock;
+	if (protocol->clock_sync_init && protocol->clock_sync_init(tsync) < 0)
+		goto error;
+
+	return 0;
+error:
+	tsync->context = NULL;
+	free(clock);
+	return -1;
+}
+
+/**
+ * tracecmd_tsync_free - Free time sync context, allocated by
+ *		tracecmd_tsync_with_host() or tracecmd_tsync_with_guest() APIs
+ *
+ * @tsync: Pointer to time sync context
+ *
+ */
+void tracecmd_tsync_free(struct tracecmd_time_sync *tsync)
+{
+	struct clock_sync_context *tsync_context;
+	struct tsync_proto *proto;
+
+	if (!tsync->context)
+		return;
+	tsync_context = (struct clock_sync_context *)tsync->context;
+
+	proto = tsync_proto_find(tsync->sync_proto);
+	if (proto && proto->clock_sync_free)
+		proto->clock_sync_free(tsync);
+
+	clock_synch_delete_instance(tsync_context->vinst);
+	tsync_context->vinst = NULL;
+
+	free(tsync_context->sync_ts);
+	free(tsync_context->sync_offsets);
+	tsync_context->sync_ts = NULL;
+	tsync_context->sync_offsets = NULL;
+	tsync_context->sync_count = 0;
+	tsync_context->sync_size = 0;
+	pthread_mutex_destroy(&tsync->lock);
+	pthread_cond_destroy(&tsync->cond);
+	free(tsync->clock_str);
+}
+
+int tracecmd_tsync_send(struct tracecmd_time_sync *tsync,
+				  struct tsync_proto *proto)
+{
+	long long timestamp = 0;
+	long long offset = 0;
+	int ret;
+
+	ret = proto->clock_sync_calc(tsync, &offset, &timestamp);
+
+	return ret;
+}
+
+/**
+ * tracecmd_tsync_with_host - Synchronize timestamps with host
+ *
+ * @tsync: Pointer to time sync context
+ *
+ * This API is supposed to be called in guest context. It waits for a time
+ * sync request from the host and replies with a time sample, until time sync
+ * stop command is received
+ *
+ */
+void tracecmd_tsync_with_host(struct tracecmd_time_sync *tsync)
+{
+	struct tsync_proto *proto;
+	unsigned int protocol;
+	unsigned int command;
+	int ret;
+
+	proto = tsync_proto_find(tsync->sync_proto);
+	if (!proto || !proto->clock_sync_calc)
+		return;
+
+	clock_context_init(tsync, true);
+	if (!tsync->context)
+		return;
+
+	while (true) {
+		ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+						  &protocol, &command,
+						  NULL, NULL);
+
+		if (ret ||
+		    protocol != TRACECMD_TIME_SYNC_PROTO_NONE ||
+		    command != TRACECMD_TIME_SYNC_CMD_PROBE)
+			break;
+		ret = tracecmd_tsync_send(tsync, proto);
+		if (ret)
+			break;
+	}
+}
+
+static int tsync_get_sample(struct tracecmd_time_sync *tsync,
+			    struct tsync_proto *proto, int array_step)
+{
+	struct clock_sync_context *clock;
+	long long *sync_offsets = NULL;
+	long long *sync_ts = NULL;
+	long long timestamp = 0;
+	long long offset = 0;
+	int ret;
+
+	ret = proto->clock_sync_calc(tsync, &offset, &timestamp);
+	if (ret) {
+		warning("Failed to synchronize timestamps with guest");
+		return -1;
+	}
+	if (!offset || !timestamp)
+		return 0;
+	clock = tsync->context;
+	if (clock->sync_count >= clock->sync_size) {
+		sync_ts = realloc(clock->sync_ts,
+				  (clock->sync_size + array_step) * sizeof(long long));
+		sync_offsets = realloc(clock->sync_offsets,
+				       (clock->sync_size + array_step) * sizeof(long long));
+		if (!sync_ts || !sync_offsets) {
+			free(sync_ts);
+			free(sync_offsets);
+			return -1;
+		}
+		clock->sync_size += array_step;
+		clock->sync_ts = sync_ts;
+		clock->sync_offsets = sync_offsets;
+	}
+
+	clock->sync_ts[clock->sync_count] = timestamp;
+	clock->sync_offsets[clock->sync_count] = offset;
+	clock->sync_count++;
+
+	return 0;
+}
+
+#define TIMER_SEC_NANO 1000000000LL
+static inline void get_ts_loop_delay(struct timespec *timeout, int delay_ms)
+{
+	memset(timeout, 0, sizeof(struct timespec));
+	clock_gettime(CLOCK_REALTIME, timeout);
+
+	timeout->tv_nsec += ((unsigned long long)delay_ms * 1000000LL);
+
+	if (timeout->tv_nsec >= TIMER_SEC_NANO) {
+		timeout->tv_sec += timeout->tv_nsec / TIMER_SEC_NANO;
+		timeout->tv_nsec %= TIMER_SEC_NANO;
+	}
+}
+
+#define CLOCK_TS_ARRAY 5
+/**
+ * tracecmd_tsync_with_guest - Synchronize timestamps with guest
+ *
+ * @tsync: Pointer to time sync context
+ *
+ * This API is supposed to be called in host context, in a separate thread
+ * It loops infinite, until the timesync semaphore is released
+ *
+ */
+void tracecmd_tsync_with_guest(struct tracecmd_time_sync *tsync)
+{
+	int ts_array_size = CLOCK_TS_ARRAY;
+	struct tsync_proto *proto;
+	struct timespec timeout;
+	bool end = false;
+	int ret;
+
+	proto = tsync_proto_find(tsync->sync_proto);
+	if (!proto || !proto->clock_sync_calc)
+		return;
+
+	clock_context_init(tsync, false);
+	if (!tsync->context)
+		return;
+
+	if (tsync->loop_interval > 0 &&
+	    tsync->loop_interval < (CLOCK_TS_ARRAY * 1000))
+		ts_array_size = (CLOCK_TS_ARRAY * 1000) / tsync->loop_interval;
+
+	while (true) {
+		pthread_mutex_lock(&tsync->lock);
+		ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+						  TRACECMD_TIME_SYNC_PROTO_NONE,
+						  TRACECMD_TIME_SYNC_CMD_PROBE,
+						  0, NULL);
+		ret = tsync_get_sample(tsync, proto, ts_array_size);
+		if (ret || end)
+			break;
+		if (tsync->loop_interval > 0) {
+			get_ts_loop_delay(&timeout, tsync->loop_interval);
+			ret = pthread_cond_timedwait(&tsync->cond, &tsync->lock, &timeout);
+			pthread_mutex_unlock(&tsync->lock);
+			if (ret && ret != ETIMEDOUT)
+				break;
+			else if (!ret)
+				end = true;
+		} else {
+			pthread_cond_wait(&tsync->cond, &tsync->lock);
+			end = true;
+		}
+	};
+
+	tracecmd_msg_send_time_sync(tsync->msg_handle,
+				    TRACECMD_TIME_SYNC_PROTO_NONE,
+				    TRACECMD_TIME_SYNC_CMD_STOP,
+				    0, NULL);
+}
diff --git a/tracecmd/Makefile b/tracecmd/Makefile
index 29a623b..908dab2 100644
--- a/tracecmd/Makefile
+++ b/tracecmd/Makefile
@@ -30,6 +30,7 @@ TRACE_CMD_OBJS += trace-check-events.o
 TRACE_CMD_OBJS += trace-show.o
 TRACE_CMD_OBJS += trace-list.o
 TRACE_CMD_OBJS += trace-usage.o
+TRACE_CMD_OBJS += trace-tsync.o
 
 ifeq ($(VSOCK_DEFINED), 1)
 TRACE_CMD_OBJS += trace-agent.o
@@ -42,7 +43,7 @@ all_objs := $(sort $(ALL_OBJS))
 all_deps := $(all_objs:$(bdir)/%.o=$(bdir)/.%.d)
 
 CONFIG_INCLUDES =
-CONFIG_LIBS	= -lrt
+CONFIG_LIBS	= -lrt -lpthread
 CONFIG_FLAGS	=
 
 all: $(TARGETS)
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index d3e96c2..4a8125b 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -228,6 +228,10 @@ struct buffer_instance {
 	unsigned int		port;
 	int			*fds;
 	bool			use_fifos;
+
+	pthread_t		tsync_thread;
+	bool			tsync_thread_running;
+	struct tracecmd_time_sync tsync;
 };
 
 void init_top_instance(void);
@@ -262,6 +266,13 @@ void tracecmd_disable_tracing(void);
 void tracecmd_enable_tracing(void);
 void tracecmd_stat_cpu(struct trace_seq *s, int cpu);
 
+int tracecmd_host_tsync(struct buffer_instance *instance,
+			 unsigned int tsync_port);
+void tracecmd_host_tsync_complete(struct buffer_instance *instance);
+unsigned int tracecmd_guest_tsync(char *tsync_protos,
+				  unsigned int tsync_protos_size, char *clock,
+				  unsigned int *tsync_port, pthread_t *thr_id);
+
 int trace_make_vsock(unsigned int port);
 int trace_get_vsock_port(int sd, unsigned int *port);
 int trace_open_vsock(unsigned int cid, unsigned int port);
diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c
index db58064..d58e5e5 100644
--- a/tracecmd/trace-agent.c
+++ b/tracecmd/trace-agent.c
@@ -19,6 +19,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 #include <linux/vm_sockets.h>
+#include <pthread.h>
 
 #include "trace-local.h"
 #include "trace-msg.h"
@@ -125,11 +126,30 @@ cleanup:
 	return ret;
 }
 
+static char *get_clock(int argc, char **argv)
+{
+	int i;
+
+	if (!argc || !argv)
+		return NULL;
+
+	for (i = 0; i < argc - 1; i++) {
+		if (!strcmp("-C", argv[i]))
+			return argv[i+1];
+	}
+	return NULL;
+}
+
 static void agent_handle(int sd, int nr_cpus, int page_size)
 {
 	struct tracecmd_msg_handle *msg_handle;
+	unsigned int tsync_protos_size = 0;
+	unsigned int tsync_proto = 0;
 	unsigned long long trace_id;
+	unsigned int tsync_port = 0;
+	char *tsync_protos = NULL;
 	unsigned int *ports;
+	pthread_t sync_thr;
 	char **argv = NULL;
 	int argc = 0;
 	bool use_fifos;
@@ -146,7 +166,8 @@ static void agent_handle(int sd, int nr_cpus, int page_size)
 		die("Failed to allocate message handle");
 
 	ret = tracecmd_msg_recv_trace_req(msg_handle, &argc, &argv,
-					  &use_fifos, &trace_id);
+					  &use_fifos, &trace_id,
+					  &tsync_protos, &tsync_protos_size);
 	if (ret < 0)
 		die("Failed to receive trace request");
 
@@ -155,14 +176,27 @@ static void agent_handle(int sd, int nr_cpus, int page_size)
 
 	if (!use_fifos)
 		make_vsocks(nr_cpus, fds, ports);
+	if (tsync_protos) {
+		tsync_proto = tracecmd_guest_tsync(tsync_protos,
+						   tsync_protos_size,
+						   get_clock(argc, argv),
+						   &tsync_port, &sync_thr);
+		if (!tsync_proto)
+			warning("Failed to negotiate timestamps synchronization with the host");
+	}
 	trace_id = tracecmd_generate_traceid();
 	ret = tracecmd_msg_send_trace_resp(msg_handle, nr_cpus, page_size,
-					   ports, use_fifos, trace_id);
+					   ports, use_fifos, trace_id,
+					   tsync_proto, tsync_port);
 	if (ret < 0)
 		die("Failed to send trace response");
 	trace_record_agent(msg_handle, nr_cpus, fds, argc, argv,
 			   use_fifos, trace_id);
 
+	if (tsync_proto)
+		pthread_join(sync_thr, NULL);
+
+	free(tsync_protos);
 	free(argv[0]);
 	free(argv);
 	free(ports);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index e84b714..6654b5b 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -670,6 +670,11 @@ static void tell_guests_to_stop(void)
 			tracecmd_msg_send_close_msg(instance->msg_handle);
 	}
 
+	for_all_instances(instance) {
+		if (is_guest(instance))
+			tracecmd_host_tsync_complete(instance);
+	}
+
 	/* Wait for guests to acknowledge */
 	for_all_instances(instance) {
 		if (is_guest(instance)) {
@@ -3498,6 +3503,10 @@ static void connect_to_agent(struct buffer_instance *instance)
 {
 	struct tracecmd_msg_handle *msg_handle;
 	int sd, ret, nr_fifos, nr_cpus, page_size;
+	unsigned int tsync_protos_reply = 0;
+	unsigned int tsync_port = 0;
+	char *protos = NULL;
+	int protos_count = 0;
 	unsigned int *ports;
 	int i, *fds = NULL;
 	bool use_fifos = false;
@@ -3517,19 +3526,33 @@ static void connect_to_agent(struct buffer_instance *instance)
 	if (!msg_handle)
 		die("Failed to allocate message handle");
 
+	if (instance->tsync.loop_interval >= 0)
+		tracecmd_tsync_proto_getall(&protos, &protos_count);
+
 	ret = tracecmd_msg_send_trace_req(msg_handle, instance->argc,
 					  instance->argv, use_fifos,
-					  top_instance.trace_id);
-
+					  top_instance.trace_id,
+					  protos, protos_count);
 	if (ret < 0)
 		die("Failed to send trace request");
 
+	free(protos);
+
 	ret = tracecmd_msg_recv_trace_resp(msg_handle, &nr_cpus, &page_size,
 					   &ports, &use_fifos,
-					   &instance->trace_id);
+					   &instance->trace_id,
+					   &tsync_protos_reply, &tsync_port);
 
 	if (ret < 0)
-		die("Failed to receive trace response");
+		die("Failed to receive trace response %d", ret);
+
+	if (protos_count && tsync_protos_reply) {
+		if (tsync_proto_is_supported(tsync_protos_reply)) {
+			instance->tsync.sync_proto = tsync_protos_reply;
+			tracecmd_host_tsync(instance, tsync_port);
+		} else
+			warning("Failed to negotiate timestamps synchronization with the guest");
+	}
 
 	if (use_fifos) {
 		if (nr_cpus != nr_fifos) {
@@ -3577,7 +3600,9 @@ static void setup_guest(struct buffer_instance *instance)
 	close(fd);
 }
 
-static void setup_agent(struct buffer_instance *instance, struct common_record_context *ctx)
+static void setup_agent(struct buffer_instance *instance,
+			struct common_record_context *ctx)
+
 {
 	struct tracecmd_output *network_handle;
 
@@ -5131,6 +5156,7 @@ void init_top_instance(void)
 }
 
 enum {
+	OPT_tsyncinterval	= 242,
 	OPT_user		= 243,
 	OPT_procmap		= 244,
 	OPT_quiet		= 245,
@@ -5433,6 +5459,7 @@ static void parse_record_options(int argc,
 			{"proc-map", no_argument, NULL, OPT_procmap},
 			{"user", required_argument, NULL, OPT_user},
 			{"module", required_argument, NULL, OPT_module},
+			{"tsync-interval", required_argument, NULL, OPT_tsyncinterval},
 			{NULL, 0, NULL, 0}
 		};
 
@@ -5775,6 +5802,10 @@ static void parse_record_options(int argc,
 			ctx->instance->filter_mod = optarg;
 			ctx->filtered = 0;
 			break;
+		case OPT_tsyncinterval:
+			top_instance.tsync.loop_interval = atoi(optarg);
+			guest_sync_set = true;
+			break;
 		case OPT_quiet:
 		case 'q':
 			quiet = true;
@@ -5804,6 +5835,7 @@ static void parse_record_options(int argc,
 					add_argv(instance, "-C", true);
 				}
 			}
+			instance->tsync.loop_interval = top_instance.tsync.loop_interval;
 		}
 	}
 
diff --git a/tracecmd/trace-tsync.c b/tracecmd/trace-tsync.c
new file mode 100644
index 0000000..7a4fc39
--- /dev/null
+++ b/tracecmd/trace-tsync.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+ *
+ */
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#include <linux/vm_sockets.h>
+#include <pthread.h>
+
+#include "trace-local.h"
+#include "trace-msg.h"
+
+static int get_first_cpu(cpu_set_t **pin_mask, size_t *m_size)
+{
+	int cpus = tracecmd_count_cpus();
+	cpu_set_t *cpu_mask;
+	int mask_size;
+	int i;
+
+	cpu_mask = CPU_ALLOC(cpus);
+	*pin_mask = CPU_ALLOC(cpus);
+	if (!cpu_mask || !*pin_mask || 1)
+		goto error;
+
+	mask_size = CPU_ALLOC_SIZE(cpus);
+	CPU_ZERO_S(mask_size, cpu_mask);
+	CPU_ZERO_S(mask_size, *pin_mask);
+
+	if (sched_getaffinity(0, mask_size, cpu_mask) == -1)
+		goto error;
+
+	for (i = 0; i < cpus; i++) {
+		if (CPU_ISSET_S(i, mask_size, cpu_mask)) {
+			CPU_SET_S(i, mask_size, *pin_mask);
+			break;
+		}
+	}
+
+	if (CPU_COUNT_S(mask_size, *pin_mask) < 1)
+		goto error;
+
+	CPU_FREE(cpu_mask);
+	*m_size = mask_size;
+	return 0;
+
+error:
+	if (cpu_mask)
+		CPU_FREE(cpu_mask);
+	if (*pin_mask)
+		CPU_FREE(*pin_mask);
+	*pin_mask = NULL;
+	*m_size = 0;
+	return -1;
+}
+
+static void *tsync_host_thread(void *data)
+{
+	struct tracecmd_time_sync *tsync = NULL;
+
+	tsync = (struct tracecmd_time_sync *)data;
+
+	tracecmd_tsync_with_guest(tsync);
+
+	tracecmd_msg_handle_close(tsync->msg_handle);
+	tsync->msg_handle = NULL;
+
+	pthread_exit(0);
+}
+
+int tracecmd_host_tsync(struct buffer_instance *instance,
+			 unsigned int tsync_port)
+{
+	struct tracecmd_msg_handle *msg_handle = NULL;
+	cpu_set_t *pin_mask = NULL;
+	pthread_attr_t attrib;
+	size_t mask_size = 0;
+	int ret;
+	int fd;
+
+	if (!instance->tsync.sync_proto)
+		return -1;
+
+	fd = trace_open_vsock(instance->cid, tsync_port);
+	if (fd < 0) {
+		ret = -1;
+		goto out;
+	}
+	msg_handle = tracecmd_msg_handle_alloc(fd, 0);
+	if (!msg_handle) {
+		ret = -1;
+		goto out;
+	}
+
+	instance->tsync.msg_handle = msg_handle;
+	if (tracecmd_get_instance_clock(top_instance.ftrace))
+		instance->tsync.clock_str = strdup(tracecmd_get_instance_clock(top_instance.ftrace));
+	pthread_mutex_init(&instance->tsync.lock, NULL);
+	pthread_cond_init(&instance->tsync.cond, NULL);
+
+	pthread_attr_init(&attrib);
+	pthread_attr_setdetachstate(&attrib, PTHREAD_CREATE_JOINABLE);
+	if (!get_first_cpu(&pin_mask, &mask_size))
+		pthread_attr_setaffinity_np(&attrib, mask_size, pin_mask);
+
+	ret = pthread_create(&instance->tsync_thread, &attrib,
+			     tsync_host_thread, &instance->tsync);
+	if (!ret)
+		instance->tsync_thread_running = true;
+	if (pin_mask)
+		CPU_FREE(pin_mask);
+	pthread_attr_destroy(&attrib);
+
+out:
+	if (ret) {
+		if (msg_handle)
+			tracecmd_msg_handle_close(msg_handle);
+	}
+
+	return ret;
+}
+
+static void write_guest_time_shift(struct buffer_instance *instance)
+{
+	struct tracecmd_output *handle;
+	struct iovec vector[4];
+	long long *offsets;
+	long long *ts;
+	char *file;
+	int count;
+	int ret;
+	int fd;
+
+	ret = tracecmd_tsync_get_offsets(&instance->tsync, &count, &ts, &offsets);
+	if (ret < 0 || !count || !ts || !offsets)
+		return;
+
+	file = trace_get_guest_file(TRACE_FILENAME,
+			      tracecmd_get_instance_name(instance->ftrace));
+	fd = open(file, O_RDWR);
+	if (fd < 0)
+		die("error opening %s", file);
+	free(file);
+	handle = tracecmd_get_output_handle_fd(fd);
+	vector[0].iov_len = 8;
+	vector[0].iov_base = &top_instance.trace_id;
+	vector[1].iov_len = 4;
+	vector[1].iov_base = &count;
+	vector[2].iov_len = 8 * count;
+	vector[2].iov_base = ts;
+	vector[3].iov_len = 8 * count;
+	vector[3].iov_base = offsets;
+	tracecmd_add_option_v(handle, TRACECMD_OPTION_TIME_SHIFT, vector, 4);
+	tracecmd_append_options(handle);
+	tracecmd_output_close(handle);
+#ifdef TSYNC_DEBUG
+	if (count > 1)
+		printf("Got %d timestamp synch samples for guest %s in %lld ns trace\n\r",
+			count, tracecmd_get_instance_name(instance->ftrace),
+			ts[count - 1] - ts[0]);
+#endif
+}
+
+void tracecmd_host_tsync_complete(struct buffer_instance *instance)
+{
+	if (!instance->tsync_thread_running)
+		return;
+
+	pthread_mutex_lock(&instance->tsync.lock);
+	pthread_cond_signal(&instance->tsync.cond);
+	pthread_mutex_unlock(&instance->tsync.lock);
+	pthread_join(instance->tsync_thread, NULL);
+	write_guest_time_shift(instance);
+	tracecmd_tsync_free(&instance->tsync);
+}
+
+static void *tsync_agent_thread(void *data)
+{
+	struct tracecmd_time_sync *tsync = NULL;
+	int sd;
+
+	tsync = (struct tracecmd_time_sync *)data;
+
+	while (true) {
+		sd = accept(tsync->msg_handle->fd, NULL, NULL);
+		if (sd < 0) {
+			if (errno == EINTR)
+				continue;
+			goto out;
+		}
+		break;
+	}
+	close(tsync->msg_handle->fd);
+	tsync->msg_handle->fd = sd;
+
+	tracecmd_tsync_with_host(tsync);
+
+out:
+	tracecmd_msg_handle_close(tsync->msg_handle);
+	tracecmd_tsync_free(tsync);
+	free(tsync);
+	close(sd);
+
+	pthread_exit(0);
+}
+
+unsigned int tracecmd_guest_tsync(char *tsync_protos,
+				  unsigned int tsync_protos_size, char *clock,
+				  unsigned int *tsync_port, pthread_t *thr_id)
+{
+	struct tracecmd_time_sync *tsync = NULL;
+	cpu_set_t *pin_mask = NULL;
+	pthread_attr_t attrib;
+	size_t mask_size = 0;
+	unsigned int proto;
+	int ret;
+	int fd;
+
+	fd = -1;
+	proto = tracecmd_tsync_proto_select(tsync_protos, tsync_protos_size);
+	if (!proto)
+		return 0;
+#ifdef VSOCK
+	fd = trace_make_vsock(VMADDR_PORT_ANY);
+	if (fd < 0)
+		goto error;
+
+	ret = trace_get_vsock_port(fd, tsync_port);
+	if (ret < 0)
+		goto error;
+#else
+	return 0;
+#endif
+
+	tsync = calloc(1, sizeof(struct tracecmd_time_sync));
+	tsync->msg_handle = tracecmd_msg_handle_alloc(fd, 0);
+	if (clock)
+		tsync->clock_str = strdup(clock);
+
+	pthread_attr_init(&attrib);
+	tsync->sync_proto = proto;
+	pthread_attr_setdetachstate(&attrib, PTHREAD_CREATE_JOINABLE);
+	if (!get_first_cpu(&pin_mask, &mask_size))
+		pthread_attr_setaffinity_np(&attrib, mask_size, pin_mask);
+
+	ret = pthread_create(thr_id, &attrib, tsync_agent_thread, tsync);
+
+	if (pin_mask)
+		CPU_FREE(pin_mask);
+	pthread_attr_destroy(&attrib);
+
+	if (ret)
+		goto error;
+
+	return proto;
+
+error:
+	if (tsync) {
+		if (tsync->msg_handle)
+			tracecmd_msg_handle_close(tsync->msg_handle);
+		if (tsync->clock_str)
+			free(tsync->clock_str);
+		free(tsync);
+	}
+	if (fd > 0)
+		close(fd);
+	return 0;
+}
diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
index 05ec021..9fa61e1 100644
--- a/tracecmd/trace-usage.c
+++ b/tracecmd/trace-usage.c
@@ -60,6 +60,10 @@ static struct usage_help usage_help[] = {
 		"          --no-filter include trace-cmd threads in the trace\n"
 		"          --proc-map save the traced processes address map into the trace.dat file\n"
 		"          --user execute the specified [command ...] as given user\n"
+		"          --tsync-interval set the loop interval, in ms, for timestamps synchronization with guests:"
+		"               If a negative number is specified, timestamps synchronization is disabled"
+		"               If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
+		"                                                         at the beginnig and at the end of the trace\n"
 	},
 	{
 		"start",
-- 
2.23.0

[PATCH v18 17/18] trace-cmd: [POC] PTP-like algorithm for host - guest timestamp synchronization

[Tzvetomir Stoyanov (VMware)]

PTP protocol is designed for synchronizing clocks of machines in a local network.
The same approach can be used for host - guest timestamp synchronization.
This implementation uses ftrace raw markers to track trace timestamps of PTP events.
The patch is a POC, two different algorithms for PTP calculations are proposed:
  - Choosing the sample with the fastest response time for calculating the clocks offset.
  - Calculating the clocks offset using the average of all PTP samples.

The implementation can be tuned using those parameters:
 - #define FASTEST_RESPONSE - is defined, the sample with the fastest response time
    is used for calculating the clocks offset. Otherwise the histogram of all samples is used.
 - #define PTP_SYNC_LOOP 340 - defines the number of samples, used for one calculation.
 - --tsync-interval - a trace-cmd argument, choose the intervals between offset calculations,
	performed continuously during the trace.
 - #define TSYNC_DEBUG - if defined, a debug information is collected and stored in files,
   in the guest machine:
     s-cid*.txt - For each offset calculation: host and guest clocks and calculated offset.
     res-cid*.txt - For each tracing session: all calculated clock offsets.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 include/trace-cmd/trace-cmd.h      |   1 +
 lib/trace-cmd/Makefile             |   1 +
 lib/trace-cmd/trace-timesync-ptp.c | 649 +++++++++++++++++++++++++++++
 lib/trace-cmd/trace-timesync.c     |   8 +
 tracecmd/trace-agent.c             |   2 +
 tracecmd/trace-record.c            |  25 +-
 6 files changed, 678 insertions(+), 8 deletions(-)
 create mode 100644 lib/trace-cmd/trace-timesync-ptp.c

diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
index bf52785..45f7eae 100644
--- a/include/trace-cmd/trace-cmd.h
+++ b/include/trace-cmd/trace-cmd.h
@@ -430,6 +430,7 @@ int tracecmd_iterate_raw_events(struct tep_handle *tep,
 
 enum{
 	TRACECMD_TIME_SYNC_PROTO_NONE	= 0,
+	TRACECMD_TIME_SYNC_PROTO_PTP	= 1,
 };
 enum{
 	TRACECMD_TIME_SYNC_CMD_PROBE	= 1,
diff --git a/lib/trace-cmd/Makefile b/lib/trace-cmd/Makefile
index 6221b36..a2b9d08 100644
--- a/lib/trace-cmd/Makefile
+++ b/lib/trace-cmd/Makefile
@@ -17,6 +17,7 @@ OBJS += trace-instance.o
 OBJS += trace-filter-hash.o
 OBJS += trace-msg.o
 OBJS += trace-timesync.o
+OBJS += trace-timesync-ptp.o
 
 # Additional util objects
 OBJS += trace-blk-hack.o
diff --git a/lib/trace-cmd/trace-timesync-ptp.c b/lib/trace-cmd/trace-timesync-ptp.c
new file mode 100644
index 0000000..6a5f5b7
--- /dev/null
+++ b/lib/trace-cmd/trace-timesync-ptp.c
@@ -0,0 +1,649 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * Copyright (C) 2019, VMware, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
+ *
+ */
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <linux/vm_sockets.h>
+#include <sys/types.h>
+#include <linux/types.h>
+#include <time.h>
+#include <sched.h>
+#include "trace-cmd.h"
+#include "trace-tsync-local.h"
+#include "trace-msg.h"
+
+typedef __be32 be32;
+typedef __u64 u64;
+typedef __s64 s64;
+
+#define PTP_SYNC_LOOP	340
+
+#define PTP_SYNC_PKT_START	1
+#define PTP_SYNC_PKT_PROBE	2
+#define PTP_SYNC_PKT_PROBES	3
+#define PTP_SYNC_PKT_OFFSET	4
+#define PTP_SYNC_PKT_END	5
+
+#define TSYNC_DEBUG
+
+struct ptp_clock_sync {
+	struct tep_handle	*tep;
+	int			raw_id;
+	int			marker_fd;
+	int			series_id;
+	int			debug_fd;
+
+};
+
+struct ptp_clock_start_msg {
+	be32	series_id;
+} __attribute__((packed));
+
+struct ptp_clock_sample {
+	s64		ts;
+	be32		id;
+} __attribute__((packed));
+
+struct ptp_clock_result_msg {
+	be32			series_id;
+	be32			count;
+	struct ptp_clock_sample	samples[2*PTP_SYNC_LOOP];
+} __attribute__((packed));
+
+struct ptp_clock_offset_msg {
+	s64	ts;
+	s64	offset;
+};
+
+struct ptp_markers_context {
+	struct clock_sync_context	*clock;
+	struct ptp_clock_sync		*ptp;
+	int				size;
+	struct ptp_clock_result_msg	msg;
+};
+
+struct ptp_marker_buf {
+	int local_cid;
+	int remote_cid;
+	int count;
+	int packet_id;
+} __attribute__((packed));
+
+struct ptp_marker{
+	int series_id;
+	struct ptp_marker_buf data;
+} __attribute__((packed));
+
+static int ptp_clock_sync_init(struct tracecmd_time_sync *tsync)
+{
+	const char *systems[] = { "ftrace", NULL};
+	struct clock_sync_context *clock_context;
+	struct ptp_clock_sync *ptp;
+	struct tep_event *raw;
+	char *path;
+
+	if (!tsync || !tsync->context)
+		return -1;
+	clock_context = (struct clock_sync_context *)tsync->context;
+	if (clock_context->proto_data)
+		return 0;
+
+	ptp = calloc(1, sizeof(struct ptp_clock_sync));
+	if (!ptp)
+		return -1;
+
+	ptp->marker_fd = -1;
+	ptp->debug_fd = -1;
+
+	path = tracecmd_get_instance_dir(clock_context->vinst);
+	if (!path)
+		goto error;
+	ptp->tep = tracecmd_local_events_system(path, systems);
+	tracecmd_put_tracing_file(path);
+	if (!ptp->tep)
+		goto error;
+	raw = tep_find_event_by_name(ptp->tep, "ftrace", "raw_data");
+	if (!raw)
+		goto error;
+
+	ptp->raw_id = raw->id;
+	tep_set_file_bigendian(ptp->tep, tracecmd_host_bigendian());
+	tep_set_local_bigendian(ptp->tep, tracecmd_host_bigendian());
+
+	path = tracecmd_get_instance_file(clock_context->vinst, "trace_marker_raw");
+	if (!path)
+		goto error;
+	ptp->marker_fd = open(path, O_WRONLY);
+	tracecmd_put_tracing_file(path);
+
+	clock_context->proto_data = ptp;
+
+#ifdef TSYNC_DEBUG
+	if (clock_context->server) {
+		char buff[256];
+		int res_fd;
+
+		sprintf(buff, "res-cid%d.txt", clock_context->remote_cid);
+
+		res_fd = open(buff, O_CREAT|O_WRONLY|O_TRUNC, 0644);
+		if (res_fd > 0)
+			close(res_fd);
+	}
+#endif
+
+	return 0;
+
+error:
+	if (ptp) {
+		tep_free(ptp->tep);
+		if (ptp->marker_fd >= 0)
+			close(ptp->marker_fd);
+	}
+	free(ptp);
+	return -1;
+}
+
+static int ptp_clock_sync_free(struct tracecmd_time_sync *tsync)
+{
+	struct clock_sync_context *clock_context;
+	struct ptp_clock_sync *ptp;
+
+	if (!tsync || !tsync->context)
+		return -1;
+	clock_context = (struct clock_sync_context *)tsync->context;
+
+	if (clock_context && clock_context->proto_data) {
+		ptp = (struct ptp_clock_sync *)clock_context->proto_data;
+		tep_free(ptp->tep);
+		if (ptp->marker_fd >= 0)
+			close(ptp->marker_fd);
+		if (ptp->debug_fd >= 0)
+			close(ptp->debug_fd);
+		free(clock_context->proto_data);
+		clock_context->proto_data = NULL;
+	}
+	return 0;
+}
+
+static int ptp_marker_find(struct tep_event *event, struct tep_record *record,
+			   int cpu, void *context)
+{
+	struct ptp_markers_context *ctx;
+	struct tep_format_field *field;
+	struct tep_format_field *id;
+	struct ptp_marker *marker;
+	int index = -1;
+
+	ctx = (struct ptp_markers_context *)context;
+
+	/* Make sure this is our event */
+	if (event->id != ctx->ptp->raw_id)
+		return 0;
+	id = tep_find_field(event, "id");
+	field = tep_find_field(event, "buf");
+	if (field && id &&
+	    record->size >= (id->offset + sizeof(struct ptp_marker))) {
+		marker = (struct ptp_marker *)(record->data + id->offset);
+		if (marker->data.local_cid == ctx->clock->local_cid &&
+		    marker->data.remote_cid == ctx->clock->remote_cid &&
+		    marker->series_id == ctx->ptp->series_id &&
+		    marker->data.count) {
+			if (marker->data.packet_id == 'r' &&
+			    marker->data.count <= ctx->size) {
+				index = marker->data.count - 1;
+			} else if (marker->data.packet_id == 's' &&
+				  marker->data.count*2 <= ctx->size){
+				index = ctx->size / 2 + marker->data.count - 1;
+			}
+		}
+		if (index >= 0) {
+			ctx->msg.samples[index].id = marker->data.count;
+			ctx->msg.samples[index].ts = record->ts;
+			ctx->msg.count++;
+		}
+	}
+
+	return 0;
+}
+
+//#define FASTEST_RESPONSE
+
+#ifdef FASTEST_RESPONSE
+static int ptp_calc_offset(struct clock_sync_context *clock,
+			   struct ptp_clock_result_msg *server,
+			   struct ptp_clock_result_msg *client,
+			   long long *offset_ret, long long *ts_ret,
+			   int *bad_probes)
+{
+	struct ptp_clock_sample *sample_send;
+	long long delta_min = 0;
+	long long offset = 0;
+	long long delta = 0;
+	long long ts = 0;
+	int i;
+
+	*bad_probes = 0;
+	sample_send = server->samples + (server->count / 2);
+	for (i = 0; i * 2 < server->count && i < client->count; i++) {
+		if (!server->samples[i].ts ||
+		    !sample_send[i].ts ||
+		    !client->samples[i].ts ||
+		    server->samples[i].id != sample_send[i].id ||
+		    server->samples[i].id != client->samples[i].id) {
+			(*bad_probes)++;
+			continue;
+		}
+
+		ts = (sample_send[i].ts + server->samples[i].ts) / 2;
+		offset = client->samples[i].ts - ts;
+
+		delta = server->samples[i].ts - sample_send[i].ts;
+		if (!delta_min || delta_min > delta) {
+			delta_min = delta;
+			*offset_ret = offset;
+			*ts_ret = ts;
+		}
+#ifdef TSYNC_DEBUG
+		{
+			struct ptp_clock_sync *ptp;
+
+			ptp = (struct ptp_clock_sync *)clock->proto_data;
+			if (ptp && ptp->debug_fd > 0) {
+				char buff[256];
+
+				sprintf(buff, "%lld %lld %lld\n",
+					ts, client->samples[i].ts, offset);
+				write(ptp->debug_fd, buff, strlen(buff));
+			}
+		}
+#endif
+	}
+
+	return 0;
+}
+
+#else /* histogram */
+
+static int ptp_calc_offset(struct clock_sync_context *clock,
+			   struct ptp_clock_result_msg *server,
+			   struct ptp_clock_result_msg *client,
+			   long long *offset_ret, long long *ts_ret,
+			   int *bad_probes)
+{
+	struct ptp_clock_sample *sample_send;
+	long long timestamps[PTP_SYNC_LOOP];
+	long long offsets[PTP_SYNC_LOOP];
+	int hist[PTP_SYNC_LOOP];
+	long long offset_max = 0;
+	long long offset_min = 0;
+	int ind, max = 0;
+	long long bin;
+	int i, k = 0;
+
+	*bad_probes = 0;
+	memset(hist, 0, sizeof(int) * PTP_SYNC_LOOP);
+	sample_send = server->samples + (server->count / 2);
+	for (i = 0; i * 2 < server->count && i < client->count; i++) {
+		if (!server->samples[i].ts ||
+		    !sample_send[i].ts ||
+		    !client->samples[i].ts ||
+		    server->samples[i].id != sample_send[i].id ||
+		    server->samples[i].id != client->samples[i].id) {
+			(*bad_probes)++;
+			continue;
+		}
+
+		timestamps[k] = (sample_send[i].ts + server->samples[i].ts) / 2;
+		offsets[k] = client->samples[i].ts - timestamps[k];
+		if (!offset_max || offset_max < llabs(offsets[k]))
+			offset_max = llabs(offsets[k]);
+		if (!offset_min || offset_min > llabs(offsets[k]))
+			offset_min = llabs(offsets[k]);
+#ifdef TSYNC_DEBUG
+		{
+			struct ptp_clock_sync *ptp;
+
+			ptp = (struct ptp_clock_sync *)clock->proto_data;
+
+			if (ptp && ptp->debug_fd > 0) {
+				char buff[256];
+
+				sprintf(buff, "%lld %lld %lld\n",
+					timestamps[k],
+					client->samples[i].ts, offsets[k]);
+				write(ptp->debug_fd, buff, strlen(buff));
+			}
+		}
+#endif
+		k++;
+	}
+
+	bin = (offset_max - offset_min) / PTP_SYNC_LOOP;
+	for (i = 0; i < k; i++) {
+		ind = (llabs(offsets[i]) - offset_min) / bin;
+		if (ind < PTP_SYNC_LOOP) {
+			hist[ind]++;
+			if (max < hist[ind]) {
+				max = hist[ind];
+				*offset_ret = offsets[i];
+				*ts_ret = timestamps[i];
+			}
+		}
+	}
+
+	return 0;
+}
+#endif
+
+static void ntoh_ptp_results(struct ptp_clock_result_msg *msg)
+{
+	int i;
+
+	msg->count = ntohl(msg->count);
+	for (i = 0; i < msg->count; i++) {
+		msg->samples[i].id = ntohl(msg->samples[i].id);
+		msg->samples[i].ts = ntohll(msg->samples[i].ts);
+	}
+	msg->series_id = ntohl(msg->series_id);
+}
+
+
+static void hton_ptp_results(struct ptp_clock_result_msg *msg)
+{
+	int i;
+
+	for (i = 0; i < msg->count; i++) {
+		msg->samples[i].id = htonl(msg->samples[i].id);
+		msg->samples[i].ts = htonll(msg->samples[i].ts);
+	}
+	msg->series_id = htonl(msg->series_id);
+	msg->count = htonl(msg->count);
+}
+
+static int ptp_clock_client(struct tracecmd_time_sync *tsync,
+			    long long *offset, long long *timestamp)
+{
+	struct clock_sync_context *clock_context;
+	struct ptp_clock_offset_msg res_offset;
+	unsigned int sync_proto, sync_msg;
+	struct ptp_clock_start_msg start;
+	struct ptp_markers_context ctx;
+	struct ptp_clock_sync *ptp;
+	struct ptp_marker marker;
+	unsigned int size;
+	char *msg;
+	int count;
+	int ret;
+
+	if (!tsync || !tsync->context || !tsync->msg_handle)
+		return -1;
+
+	clock_context = (struct clock_sync_context *)tsync->context;
+	if (clock_context->proto_data == NULL)
+		return -1;
+
+	ptp = (struct ptp_clock_sync *)clock_context->proto_data;
+	size = sizeof(start);
+	msg = (char *)&start;
+	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+					  &sync_proto, &sync_msg,
+					  &size, &msg);
+	if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+	    sync_msg != PTP_SYNC_PKT_START)
+		return -1;
+	ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+					  TRACECMD_TIME_SYNC_PROTO_PTP,
+					  PTP_SYNC_PKT_START, sizeof(start),
+					  (char *)&start);
+	marker.data.local_cid = clock_context->local_cid;
+	marker.data.remote_cid = clock_context->remote_cid;
+	marker.series_id = ntohl(start.series_id);
+	marker.data.packet_id = 'r';
+	ptp->series_id = marker.series_id;
+	msg = (char *)&count;
+	size = sizeof(count);
+	while (true) {
+		count = 0;
+		ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+						  &sync_proto, &sync_msg,
+						  &size, &msg);
+		if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+		    sync_msg != PTP_SYNC_PKT_PROBE || !ntohl(count))
+			break;
+
+		marker.data.count = ntohl(count);
+		write(ptp->marker_fd, &marker, sizeof(marker));
+		ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+						 TRACECMD_TIME_SYNC_PROTO_PTP,
+						 PTP_SYNC_PKT_PROBE,
+						 sizeof(count), (char *)&count);
+		if (ret)
+			break;
+	}
+
+	if (sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+	    sync_msg != PTP_SYNC_PKT_END)
+		return -1;
+
+	ctx.size = PTP_SYNC_LOOP;
+	ctx.ptp = ptp;
+	ctx.clock = clock_context;
+	ctx.msg.count = 0;
+	ctx.msg.series_id = ptp->series_id;
+	tracecmd_iterate_raw_events(ptp->tep, clock_context->vinst,
+				    ptp_marker_find, &ctx);
+	hton_ptp_results(&ctx.msg);
+	ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+					  TRACECMD_TIME_SYNC_PROTO_PTP,
+					  PTP_SYNC_PKT_PROBES,
+					  sizeof(ctx.msg), (char *)&ctx.msg);
+
+	msg = (char *)&res_offset;
+	size = sizeof(res_offset);
+	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+					  &sync_proto, &sync_msg,
+					  &size, (char **)&msg);
+	if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+	    sync_msg != PTP_SYNC_PKT_OFFSET)
+		return -1;
+
+	*offset = ntohll(res_offset.offset);
+	*timestamp = ntohll(res_offset.ts);
+
+	return 0;
+}
+
+
+static int ptp_clock_server(struct tracecmd_time_sync *tsync,
+			    long long *offset, long long *timestamp)
+{
+	struct ptp_clock_result_msg *results = NULL;
+	struct clock_sync_context *clock_context;
+	struct ptp_clock_offset_msg res_offset;
+	unsigned int sync_proto, sync_msg;
+	struct ptp_clock_start_msg start;
+	struct ptp_markers_context ctx;
+	int sync_loop = PTP_SYNC_LOOP;
+	struct ptp_clock_sync *ptp;
+	struct ptp_marker marker;
+	unsigned int size;
+	int bad_probes;
+	int count = 1;
+	int msg_count;
+	int msg_ret;
+	char *msg;
+	int ret;
+
+	if (!tsync || !tsync->context || !tsync->msg_handle)
+		return -1;
+
+	clock_context = (struct clock_sync_context *)tsync->context;
+	if (clock_context->proto_data == NULL)
+		return -1;
+
+	ptp = (struct ptp_clock_sync *)clock_context->proto_data;
+	start.series_id = htonl(ptp->series_id + 1);
+	ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+					 TRACECMD_TIME_SYNC_PROTO_PTP,
+					 PTP_SYNC_PKT_START, sizeof(start),
+					 (char *)&start);
+	if (!ret)
+		ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+						  &sync_proto, &sync_msg,
+						  NULL, NULL);
+	if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+	    sync_msg != PTP_SYNC_PKT_START)
+		return -1;
+
+	tracecmd_write_instance_file(clock_context->vinst, "trace", "\0", NULL);
+
+	ptp->series_id++;
+	marker.data.local_cid = clock_context->local_cid;
+	marker.data.remote_cid = clock_context->remote_cid;
+	marker.series_id = ptp->series_id;
+	msg = (char *)&msg_ret;
+	size = sizeof(msg_ret);
+	do {
+		marker.data.count = count++;
+		marker.data.packet_id = 's';
+		msg_count = htonl(marker.data.count);
+		write(ptp->marker_fd, &marker, sizeof(marker));
+		ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+						 TRACECMD_TIME_SYNC_PROTO_PTP,
+						 PTP_SYNC_PKT_PROBE,
+						 sizeof(msg_count),
+						 (char *)&msg_count);
+		if (!ret)
+			ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+							  &sync_proto, &sync_msg,
+							  &size, &msg);
+
+		marker.data.packet_id = 'r';
+		write(ptp->marker_fd, &marker, sizeof(marker));
+		if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+		    sync_msg != PTP_SYNC_PKT_PROBE ||
+		    ntohl(msg_ret) != marker.data.count)
+			break;
+	} while (--sync_loop);
+
+	if (sync_loop)
+		return -1;
+
+	ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+					  TRACECMD_TIME_SYNC_PROTO_PTP,
+					  PTP_SYNC_PKT_END, 0, NULL);
+
+	size = 0;
+	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
+					  &sync_proto, &sync_msg,
+					  &size, (char **)&results);
+	if (ret || sync_proto != TRACECMD_TIME_SYNC_PROTO_PTP ||
+	    sync_msg != PTP_SYNC_PKT_PROBES || size == 0 || results == NULL)
+		return -1;
+
+	ntoh_ptp_results(results);
+
+	ctx.size = 2*PTP_SYNC_LOOP;
+	ctx.ptp = ptp;
+	ctx.clock = clock_context;
+	ctx.msg.count = 0;
+	ctx.msg.series_id = ptp->series_id;
+	tracecmd_iterate_raw_events(ptp->tep, clock_context->vinst,
+				    ptp_marker_find, &ctx);
+
+	ptp_calc_offset(clock_context, &ctx.msg, results, offset,
+			timestamp, &bad_probes);
+
+#ifdef TSYNC_DEBUG
+	{
+		char buff[256];
+		int res_fd;
+
+		sprintf(buff, "res-cid%d.txt", clock_context->remote_cid);
+
+		res_fd = open(buff, O_WRONLY|O_APPEND, 0644);
+		if (res_fd > 0) {
+			if (*offset && *timestamp) {
+				sprintf(buff, "%d %lld %lld\n",
+					ptp->series_id, *offset, *timestamp);
+				write(res_fd, buff, strlen(buff));
+			}
+			close(res_fd);
+		}
+
+		printf("\n calculated offset %d: %lld, %d probes, filtered out %d\n\r",
+			ptp->series_id, *offset, results->count, bad_probes);
+		if (ptp && ptp->debug_fd > 0) {
+			sprintf(buff, "%lld %lld 0\n", *offset, *timestamp);
+			write(ptp->debug_fd, buff, strlen(buff));
+			close(ptp->debug_fd);
+			ptp->debug_fd = -1;
+		}
+
+	}
+#endif
+
+	res_offset.offset = htonll(*offset);
+	res_offset.ts = htonll(*timestamp);
+	ret = tracecmd_msg_send_time_sync(tsync->msg_handle,
+					  TRACECMD_TIME_SYNC_PROTO_PTP,
+					  PTP_SYNC_PKT_OFFSET,
+					  sizeof(res_offset),
+					  (char *)&res_offset);
+
+	free(results);
+	return 0;
+}
+
+static int ptp_clock_sync_calc(struct tracecmd_time_sync *tsync,
+			       long long *offset, long long *timestamp)
+{
+	struct clock_sync_context *clock_context;
+	int ret;
+
+	if (!tsync || !tsync->context)
+		return -1;
+	clock_context = (struct clock_sync_context *)tsync->context;
+
+#ifdef TSYNC_DEBUG
+	if (clock_context->server) {
+		struct ptp_clock_sync *ptp;
+		char buff[256];
+
+		ptp = (struct ptp_clock_sync *)clock_context->proto_data;
+		if (ptp->debug_fd > 0)
+			close(ptp->debug_fd);
+		sprintf(buff, "s-cid%d_%d.txt",
+				clock_context->remote_cid, ptp->series_id+1);
+		ptp->debug_fd = open(buff, O_CREAT|O_WRONLY|O_TRUNC, 0644);
+	}
+#endif
+
+
+	if (clock_context->server)
+		ret = ptp_clock_server(tsync, offset, timestamp);
+	else
+		ret = ptp_clock_client(tsync, offset, timestamp);
+
+	return ret;
+}
+
+int ptp_clock_sync_register(void)
+{
+	return tracecmd_tsync_proto_register(TRACECMD_TIME_SYNC_PROTO_PTP,
+					     TRACECMD_TIME_SYNC_PROTO_PTP_WEIGHT,
+					     ptp_clock_sync_init,
+					     ptp_clock_sync_free,
+					     ptp_clock_sync_calc);
+
+}
+
+int ptp_clock_sync_unregister(void)
+{
+	return tracecmd_tsync_proto_unregister(TRACECMD_TIME_SYNC_PROTO_PTP);
+}
diff --git a/lib/trace-cmd/trace-timesync.c b/lib/trace-cmd/trace-timesync.c
index 6f23a63..d5620cf 100644
--- a/lib/trace-cmd/trace-timesync.c
+++ b/lib/trace-cmd/trace-timesync.c
@@ -45,6 +45,14 @@ static struct tsync_proto *tsync_proto_find(unsigned int proto_id)
 	return NULL;
 }
 
+/**
+ * tracecmd_tsync_init - Initialize the global, per task, time sync data.
+ */
+void tracecmd_tsync_init(void)
+{
+	ptp_clock_sync_register();
+}
+
 int tracecmd_tsync_proto_register(unsigned int proto_id, int weight,
 				int (*init)(struct tracecmd_time_sync *),
 				int (*free)(struct tracecmd_time_sync *),
diff --git a/tracecmd/trace-agent.c b/tracecmd/trace-agent.c
index d58e5e5..37c7438 100644
--- a/tracecmd/trace-agent.c
+++ b/tracecmd/trace-agent.c
@@ -246,6 +246,8 @@ static void agent_serve(unsigned int port)
 	if (sd < 0)
 		die("Failed to open vsocket");
 
+	tracecmd_tsync_init();
+
 	if (!get_local_cid(&cid))
 		printf("listening on @%u:%u\n", cid, port);
 
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 6654b5b..ba14969 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -5952,10 +5952,7 @@ static void set_clock(struct buffer_instance *instance)
 		tracecmd_put_tracing_file(path);
 	}
 }
-/*
- * This function contains common code for the following commands:
- * record, start, stream, profile.
- */
+
 static void record_trace(int argc, char **argv,
 			 struct common_record_context *ctx)
 {
@@ -6088,12 +6085,24 @@ static void record_trace(int argc, char **argv,
 	finalize_record_trace(ctx);
 }
 
+/*
+ * This function contains common code for the following commands:
+ * record, start, stream, profile.
+ */
+static void record_trace_command(int argc, char **argv,
+				 struct common_record_context *ctx)
+{
+	tracecmd_tsync_init();
+	record_trace(argc, argv, ctx);
+}
+
+
 void trace_start(int argc, char **argv)
 {
 	struct common_record_context ctx;
 
 	parse_record_options(argc, argv, CMD_start, &ctx);
-	record_trace(argc, argv, &ctx);
+	record_trace_command(argc, argv, &ctx);
 	exit(0);
 }
 
@@ -6173,7 +6182,7 @@ void trace_stream(int argc, char **argv)
 	struct common_record_context ctx;
 
 	parse_record_options(argc, argv, CMD_stream, &ctx);
-	record_trace(argc, argv, &ctx);
+	record_trace_command(argc, argv, &ctx);
 	exit(0);
 }
 
@@ -6192,7 +6201,7 @@ void trace_profile(int argc, char **argv)
 	if (!buffer_instances)
 		top_instance.flags |= BUFFER_FL_PROFILE;
 
-	record_trace(argc, argv, &ctx);
+	record_trace_command(argc, argv, &ctx);
 	do_trace_profile();
 	exit(0);
 }
@@ -6211,7 +6220,7 @@ void trace_record(int argc, char **argv)
 	struct common_record_context ctx;
 
 	parse_record_options(argc, argv, CMD_record, &ctx);
-	record_trace(argc, argv, &ctx);
+	record_trace_command(argc, argv, &ctx);
 	exit(0);
 }
 
-- 
2.23.0

[PATCH v18 18/18] trace-cmd: Debug scripts for PTP-like algorithm for host - guest timestamp synchronization

[Tzvetomir Stoyanov (VMware)]

These scripts can be used to visualise debug files, written when the PTP-like algorithm
is compiled with TSYNC_DEBUG defined. The files are located in the guest machine:
    s-cid*.txt - For each offset calculation: host and guest clocks and calculated offset.
    res-cid*.txt - For each tracing session: all calculated clock offsets.

tsync_hist.py plots a histogram, using data from a s-cid*.txt file:
	"python tsync_hist.py s-cid2_1.txt"
tsync_res.py plots a line, using data from res-cid*.txt file:
	"python tsync_res.py res-cid2.txt"

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 scripts/debug/tsync_hist.py | 57 +++++++++++++++++++++++++++++++++++++
 scripts/debug/tsync_readme  | 12 ++++++++
 scripts/debug/tsync_res.py  | 46 ++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 scripts/debug/tsync_hist.py
 create mode 100644 scripts/debug/tsync_readme
 create mode 100644 scripts/debug/tsync_res.py

diff --git a/scripts/debug/tsync_hist.py b/scripts/debug/tsync_hist.py
new file mode 100644
index 0000000..819d1e8
--- /dev/null
+++ b/scripts/debug/tsync_hist.py
@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2019, VMware Inc, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+# Copyright (C) 2019, VMware Inc, Yordan Karadzhov <ykaradzhov@vmware.com>
+
+
+import matplotlib.pyplot as plt
+import matplotlib.lines as mlines
+import numpy as np
+import sys
+
+def newline(p1, p2):
+    ax = plt.gca()
+    xmin, xmax = ax.get_xbound()
+
+    if(p2[0] == p1[0]):
+        xmin = xmax = p1[0]
+        ymin, ymax = ax.get_ybound()
+    else:
+        ymax = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmax-p1[0])
+        ymin = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmin-p1[0])
+
+    l = mlines.Line2D([xmin,xmax], [ymin,ymax], color='red')
+    ax.add_line(l)
+    return l
+
+
+data = np.loadtxt(fname = sys.argv[1])
+selected_ts  = data[-1, 1]
+selected_ofs = data[-1, 0]
+data = data[:-1,:]
+
+x = data[:, 1] - data[:, 0]
+
+mean = x.mean()
+std = x.std()
+
+num_bins = 500
+min = x.min() #+ .4 * (x.max() - x.min())
+max = x.max() #- .4 * (x.max() - x.min())
+bins = np.linspace(min, max, num_bins, endpoint = False, dtype=int)
+
+fig, ax = plt.subplots()
+
+# the histogram of the data
+n, bins, patches = ax.hist(x, bins, histtype=u'step');
+
+ax.set_xlabel('clock offset [$\mu$s]')
+ax.set_ylabel('entries')
+ax.set_title("$\sigma$=%i" % std)
+
+x1, y1 = [selected_ofs, min], [selected_ofs, max]
+newline(x1, y1)
+
+# Tweak spacing to prevent clipping of ylabel
+fig.tight_layout()
+plt.show()
diff --git a/scripts/debug/tsync_readme b/scripts/debug/tsync_readme
new file mode 100644
index 0000000..f3ebb25
--- /dev/null
+++ b/scripts/debug/tsync_readme
@@ -0,0 +1,12 @@
+PTP-like algorithm debug
+========================
+
+tsync_*.py scripts can be used to visualise debug files, written when the PTP-like algorithm
+is compiled with TSYNC_DEBUG defined. The files are located in the guest machine:
+    s-cid*.txt - For each offset calculation: host and guest clocks and calculated offset.
+    res-cid*.txt - For each tracing session: all calculated clock offsets.
+
+tsync_hist.py plots a histogram, using data from a s-cid*.txt file:
+	"python tsync_hist.py s-cid2_1.txt"
+tsync_res.py plots a line, using data from res-cid*.txt file:
+	"python tsync_res.py res-cid2.txt"
diff --git a/scripts/debug/tsync_res.py b/scripts/debug/tsync_res.py
new file mode 100644
index 0000000..7d10986
--- /dev/null
+++ b/scripts/debug/tsync_res.py
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2019, VMware Inc, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
+# Copyright (C) 2019, VMware Inc, Yordan Karadzhov <ykaradzhov@vmware.com>
+
+
+import matplotlib.pyplot as plt
+import matplotlib.lines as mlines
+import numpy as np
+import sys
+
+def newline(p1, p2):
+    ax = plt.gca()
+    xmin, xmax = ax.get_xbound()
+
+    if(p2[0] == p1[0]):
+        xmin = xmax = p1[0]
+        ymin, ymax = ax.get_ybound()
+    else:
+        ymax = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmax-p1[0])
+        ymin = p1[1]+(p2[1]-p1[1])/(p2[0]-p1[0])*(xmin-p1[0])
+
+    l = mlines.Line2D([xmin,xmax], [ymin,ymax], color='red')
+    ax.add_line(l)
+    return l
+
+data = np.loadtxt(fname = sys.argv[1])
+x = data[:, 0]
+y = data[:, 1]
+
+fig, ax = plt.subplots()
+
+ax.set_xlabel('samples (t)')
+ax.set_ylabel('clock offset')
+ax.set_title("$\delta$=%i ns" % (max(y) - min(y)))
+
+l = mlines.Line2D(x, y)
+ax.add_line(l)
+ax.set_xlim(min(x), max(x))
+ax.set_ylim(min(y), max(y) )
+
+print(min(y), max(y), max(y) - min(y))
+
+# Tweak spacing to prevent clipping of ylabel
+fig.tight_layout()
+plt.show()
-- 
2.23.0

Re: [PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file

[Steven Rostedt]

On Fri, 13 Dec 2019 17:30:21 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> The ID of the current tracing session is stored in the trace.dat file.
> A new file option is introduced:
> 	TRACECMD_OPTION_TRACEID
> The data is stored in the file as NULL terminated string:
> 	"\nTraceID: %llu\n"

If the trace ID is just a 64 bit number, why is it stored in the file
as a string?

-- Steve


> A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
> 	unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  include/trace-cmd/trace-cmd.h |  2 ++
>  lib/trace-cmd/trace-input.c   | 25 +++++++++++++++++++++++++
>  tracecmd/trace-record.c       | 15 +++++++++++++++
>  3 files changed, 42 insertions(+)
> 
> diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> index ad69313..6cc2913 100644
> --- a/include/trace-cmd/trace-cmd.h
> +++ b/include/trace-cmd/trace-cmd.h
> @@ -86,6 +86,7 @@ enum {
>  	TRACECMD_OPTION_CPUCOUNT,
>  	TRACECMD_OPTION_VERSION,
>  	TRACECMD_OPTION_PROCMAPS,
> +	TRACECMD_OPTION_TRACEID,
>  };
>  
>  enum {
> @@ -128,6 +129,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
>  void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
>  void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
>  unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
>  
>  void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
>  
> diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> index 91362f3..40d9825 100644
> --- a/lib/trace-cmd/trace-input.c
> +++ b/lib/trace-cmd/trace-input.c
> @@ -79,6 +79,7 @@ struct tracecmd_input {
>  	struct tep_plugin_list	*plugin_list;
>  	struct tracecmd_input	*parent;
>  	unsigned long		flags;
> +	unsigned long long	trace_id;
>  	int			fd;
>  	int			long_size;
>  	int			page_size;
> @@ -2169,6 +2170,15 @@ static void procmap_free(struct pid_addr_maps *maps)
>  	free(maps);
>  }
>  
> +static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
> +{
> +
> +	if (sscanf(buf, "%*s %llu", &handle->trace_id) == 1)
> +		return 0;
> +
> +	return -1;
> +}
> +
>  #define STR_PROCMAP_LINE_MAX	(PATH_MAX+22)
>  static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
>  {
> @@ -2406,6 +2416,10 @@ static int handle_options(struct tracecmd_input *handle)
>  			if (buf[size-1] == '\0')
>  				trace_pid_map_load(handle, buf);
>  			break;
> +		case TRACECMD_OPTION_TRACEID:
> +			if (buf[size-1] == '\0')
> +				trace_traceid_load(handle, buf);
> +			break;
>  		default:
>  			warning("unknown option %d", option);
>  			break;
> @@ -3507,3 +3521,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
>  {
>  	handle->show_data_func = func;
>  }
> +
> +/**
> + * tracecmd_get_traceid - get the trace id of the session
> + * @handle: input handle for the trace.dat file
> + *
> + * Returns the trace id, written in the trace file
> + */
> +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
> +{
> +	return handle->trace_id;
> +}
> diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> index 7089f7b..b65aeb2 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -3714,6 +3714,19 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
>  	trace_seq_destroy(&s);
>  }
>  
> +static void
> +add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
> +{
> +	char *str = NULL;
> +	int len;
> +
> +	len = asprintf(&str, "\nTraceID: %llu\n", instance->trace_id);
> +	if (len < 1)
> +		return;
> +	tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID, len + 1, str);
> +	free(str);
> +}
> +
>  static void
>  add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
>  {
> @@ -3817,6 +3830,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
>  	add_option_hooks(handle);
>  	add_uname(handle);
>  	add_version(handle);
> +	if (!no_top_instance())
> +		add_trace_id(handle, &top_instance);
>  }
>  
>  static void write_guest_file(struct buffer_instance *instance)

Re: [PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file

[Steven Rostedt]

On Fri, 13 Dec 2019 17:30:24 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> New trace.dat option is introduced: TRACECMD_OPTION_GUEST.
> Written in the host's trace.dat file, it contains information about
> guests, traced at the same time: guest trace ID, number of VCPUs and
> PIDs of the host tasks, running those VCPU. The data is stored in
> the file as NULL terminated string:
> 	"Guest %s %llu %d\n" -> guest name, number of VCPUs
> 	"%d %d\n" -> VCPU, PID of host task
> 	.....
> 	"%d %d\n" -> VCPU, PID of host task

Why is this a string, and not a structure?

-- Steve

Re: [PATCH v18 03/18] trace-cmd: Add implementations of htonll() and ntohll()

[Steven Rostedt]

[ Replying this time to the latest version. Same comment though ]

On Fri, 13 Dec 2019 17:30:14 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> From: Tzvetomir Stoyanov <tstoyanov@vmware.com>
> 
> Implementations of htonll() and ntohll() are added as
> macros, if they are not already defined.
> 

I'm somewhat nervous about this being in a global header, as it is
mostly generic. I wonder if we should prefix these with "tracecmd_"
just to avoid any name collisions.

We could update this later when we make trace-cmd into a library.

-- Steve


> Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
> ---
>  include/trace-cmd/trace-msg.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/include/trace-cmd/trace-msg.h b/include/trace-cmd/trace-msg.h
> index aab8a69..654ca43 100644
> --- a/include/trace-cmd/trace-msg.h
> +++ b/include/trace-cmd/trace-msg.h
> @@ -12,4 +12,14 @@
>  
>  extern unsigned int page_size;
>  
> +#ifndef htonll
> +# if __BYTE_ORDER == __LITTLE_ENDIAN
> +#define htonll(x) __bswap_64(x)
> +#define ntohll(x) __bswap_64(x)
> +#else
> +#define htonll(x) (x)
> +#define ntohll(x) (x)
> +#endif
> +#endif
> +
>  #endif /* _TRACE_MSG_H_ */

Re: [PATCH v18 04/18] trace-cmd: Add new library APIs for ftrace instances.

[Steven Rostedt]

On Fri, 13 Dec 2019 17:30:15 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> +/**
> + * tracecmd_get_instance_file - return the path to a instance file
> + * @instance: buffer instance for the file, can be NULL for the top instance
> + * @file: name of file to return
> + *
> + * Returns the path name of the @file for the given @instance
> + *
> + * Must use tracecmd_put_tracing_file() to free the returned string
> + */
> +char *
> +tracecmd_get_instance_file(struct tracecmd_instance *instance, const char *file)
> +{
> +	char *path;
> +	char *buf;
> +	int ret;
> +
> +	if (instance && instance->name) {
> +		ret = asprintf(&buf, "instances/%s/%s", instance->name, file);
> +		if (ret < 0)
> +			die("Failed to allocate name for %s/%s", instance->name, file);
> +		path = tracecmd_get_tracing_file(buf);
> +		free(buf);
> +	} else
> +		path = tracecmd_get_tracing_file(file);
> +
> +	return path;
> +}
> +
> +/**
> + * tracecmd_get_instance_file - return the path to a instance file
> + * @instance: buffer instance for the file, can be NULL for the top instance
> + * @file: name of file to return
> + *
> + * Returns the path name of the @file for the given @instance
> + *
> + * Must use tracecmd_put_tracing_file() to free the returned string

The above is a cut and paste of tracecmd_get_instance_file, not of the
instance_dir.

> + */
> +char *tracecmd_get_instance_dir(struct tracecmd_instance *instance)
> +{
> +	char *buf;
> +	char *path;
> +	int ret;
> +
> +	if (instance->name) {
> +		ret = asprintf(&buf, "instances/%s", instance->name);
> +		if (ret < 0)
> +			die("Failed to allocate for instance %s", instance->name);
> +		path = tracecmd_get_tracing_file(buf);
> +		free(buf);
> +	} else
> +		path = tracecmd_find_tracing_dir();
> +
> +	return path;
> +}
> +
> +/**
> + * tracecmd_write_instance_file - Write in trace file of specific instance
> + * @instance: buffer instance for the file, can be NULL for the top instance
> + * @file: name of the file
> + * @str: Nul terminated string, that will be written in the file
> + * @type: Nul terminated string, describing the current write operation
> + *	  Used for logging purposes
> + *
> + * Returns the number of written bytes, or -1 in case of an error
> + */
> +int tracecmd_write_instance_file(struct tracecmd_instance *instance,
> +				 const char *file, const char *str,
> +				 const char *type)

I think we should get rid of the type and move the logic that needs it
to the callers.


> +{
> +	struct stat st;
> +	char *path;
> +	int ret;
> +
> +	path = tracecmd_get_instance_file(instance, file);
> +	ret = stat(path, &st);
> +	if (ret == 0)
> +		ret = tracecmd_write_file(path, str, type);
> +	tracecmd_put_tracing_file(path);
> +
> +	return ret;
> +}
> +

[..]

> +/*
> + * tracecmd_write_file - Write in trace file
> + * @file: Full name of the trace file.
> + * @str: Null terminated string, that will be written in the file.
> + * @type: Null terminated string, describing the current write operation.
> + *	  Used for logging purposes.
> + *
> + * Returns the number of written bytes, or -1 in case of an error
> + */
> +int tracecmd_write_file(const char *file, const char *str, const char *type)
> +{
> +	char buf[BUFSIZ];
> +	int ret;
> +	int fd;
> +
> +	fd = open(file, O_WRONLY | O_TRUNC);
> +	if (fd < 0)
> +		die("opening to '%s'", file);
> +	ret = write(fd, str, strlen(str));
> +	close(fd);
> +	if (ret < 0 && type) {
> +		/* write failed */
> +		fd = open(file, O_RDONLY);
> +		if (fd < 0)
> +			die("writing to '%s'", file);
> +		/* the filter has the error */
> +		while ((ret = read(fd, buf, BUFSIZ)) > 0)
> +			fprintf(stderr, "%.*s", ret, buf);
> +		die("Failed %s of %s\n", type, file);

Yeah, the above needs to be moved to the upper layers. It even has a
comment about "the filter has the error". That's reference to the
filter file of trace events, which is the only file that really does
that.

-- Steve

> +		close(fd);
> +	}
> +	return ret;
> +}
> 

Re: [PATCH v18 12/18] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT

[Steven Rostedt]

On Fri, 13 Dec 2019 17:30:23 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> @@ -2370,6 +2489,28 @@ static int handle_options(struct tracecmd_input *handle)
>  			offset = strtoll(buf, NULL, 0);
>  			handle->ts_offset += offset;
>  			break;
> +		case TRACECMD_OPTION_TIME_SHIFT:
> +			/*
> +			 * long long int (8 bytes) trace session ID
> +			 * int (4 bytes) count of timestamp offsets.
> +			 * long long array of size [count] of times,
> +			 *      when the offsets were calculated.
> +			 * long long array of size [count] of timestamp offsets.
> +			 */
> +			if (size < 12 || handle->flags & TRACECMD_FL_IGNORE_DATE)
> +				break;
> +			handle->host.trace_id = tep_read_number(handle->pevent,
> +								buf, 8);
> +			handle->host.ts_samples_count = tep_read_number(handle->pevent,
> +									buf + 8, 4);
> +			samples_size = (8 * handle->host.ts_samples_count);
> +			if (size != (12 + (2 * samples_size)))
> +				break;
> +			handle->host.ts_samples = malloc(2 * samples_size);
> +			if (!handle->host.ts_samples)
> +				return -ENOMEM;
> +			tsync_offset_load(handle, buf + 12);
> +			break;
>  		case TRACECMD_OPTION_CPUSTAT:
>  			buf[size-1] = '\n';
>  			cpustats = realloc(cpustats, cpustats_size + size + 1);
> @@ -3078,6 +3219,8 @@ void tracecmd_close(struct tracecmd_input *handle)
>  	trace_pid_map_free(handle->pid_maps);
>  	handle->pid_maps = NULL;
>  
> +	trace_tsync_offset_free(&handle->host);

You need to add in tracecmd_buffer_instance_handle() something like:

	memset(&new_handle->host, 0, sizeof(new_handle->host));

or make a copy of it. Because if the host created sub buffers along
with the top level, you get multiple frees on the host.ts_samples, as
the new_handle will have a pointer to the original handle.

This is the same bug fixed by ca4b997b6505df3ce for trace_clock.

-- Steve


> +
>  	if (handle->flags & TRACECMD_FL_BUFFER_INSTANCE)
>  		tracecmd_close(handle->parent);
>  	else {

Re: [PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization

[Steven Rostedt]

On Fri, 13 Dec 2019 17:30:27 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:

> The infrastructure for host - guest timestamp synchronization is divided
> in two parts:
>  - logic in libtracecmd
>  - logic in trace-cmd application
> 
> The libtracecmd is extended with new trace message, MSG_TIME_SYNC, used to
> exchange time synch information between host and guest. The trace request and
> response messages are extended to handle the time synch negotiation. The logic
> is implemented in trace-timesync.c file:
>  - Register / unregister time sync protocols.
>  - Choosing what protocol will be used for a tracing session.
>  - Init common context, used by all protocols - a ftrace instance, vsockets.
>  - Invoke protocol routines to perform time synchronization.
>  - Store calculated offsets in an array.
> 
> The trace-cmd application is extended to perform timestamp synchronization.
> The main logic is in trace-tsync.c file
>  - Negotiate what time synch algorithm will be used for the tracing session.
>  - Run pthreads, to do continuous timestamp synchronization, during the trace.
>  - Store calculated offsets in guest's trace.dat file, using TRACECMD_OPTION_TIME_SHIFT option
>  - A new trace-cmd option is added, to control the timestamp synchronization:
>       --tsync-interval: set the time sync loop interval, in ms. The default
>    value is 0 - timestamp synchronization is performed twice, before and after
>    the trace. If a negative number is specified, the timestamp synchronization
>    is disabled.
> 
> Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> ---
>  Documentation/trace-cmd-record.1.txt      |   7 +
>  include/trace-cmd/trace-cmd.h             |  59 ++-
>  lib/trace-cmd/Makefile                    |   1 +
>  lib/trace-cmd/include/trace-tsync-local.h |  38 ++
>  lib/trace-cmd/trace-msg.c                 | 394 ++++++++++++++---
>  lib/trace-cmd/trace-timesync.c            | 496 ++++++++++++++++++++++
>  tracecmd/Makefile                         |   3 +-
>  tracecmd/include/trace-local.h            |  11 +
>  tracecmd/trace-agent.c                    |  38 +-
>  tracecmd/trace-record.c                   |  42 +-
>  tracecmd/trace-tsync.c                    | 271 ++++++++++++
>  tracecmd/trace-usage.c                    |   4 +
>  12 files changed, 1297 insertions(+), 67 deletions(-)
>  create mode 100644 lib/trace-cmd/include/trace-tsync-local.h
>  create mode 100644 lib/trace-cmd/trace-timesync.c
>  create mode 100644 tracecmd/trace-tsync.c
> 
> diff --git a/Documentation/trace-cmd-record.1.txt b/Documentation/trace-cmd-record.1.txt
> index 0d75e43..f5ecad5 100644
> --- a/Documentation/trace-cmd-record.1.txt
> +++ b/Documentation/trace-cmd-record.1.txt
> @@ -338,6 +338,13 @@ OPTIONS
>      the offset will also be in nanoseconds even if the displayed units are
>      in microseconds.
>  
> +*--tsync-interval*::
> +    Set the loop interval, in ms, for timestamps synchronization with guests:
> +        If a negative number is specified, timestamps synchronization is disabled
> +        If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
> +        at the beginning and at the end of the trace.
> +        Timestamps synchronization with guests works only if there is support for VSOCK.\n"
> +
>  *--stderr*::
>      Have output go to stderr instead of stdout, but the output of the command
>      executed will not be changed. This is useful if you want to monitor the
> diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> index da8eeaf..bf52785 100644
> --- a/include/trace-cmd/trace-cmd.h
> +++ b/include/trace-cmd/trace-cmd.h
> @@ -362,19 +362,38 @@ void tracecmd_msg_set_done(struct tracecmd_msg_handle *msg_handle);
>  
>  int tracecmd_msg_send_trace_req(struct tracecmd_msg_handle *msg_handle,
>  				int argc, char **argv, bool use_fifos,
> -				unsigned long long trace_id);
> +				unsigned long long trace_id,
> +				char *tsync_protos,
> +				int tsync_protos_size);
> +
>  int tracecmd_msg_recv_trace_req(struct tracecmd_msg_handle *msg_handle,
>  				int *argc, char ***argv, bool *use_fifos,
> -				unsigned long long *trace_id);
> +				unsigned long long *trace_id,
> +				char **tsync_protos,
> +				unsigned int *tsync_protos_size);
>  
>  int tracecmd_msg_send_trace_resp(struct tracecmd_msg_handle *msg_handle,
>  				 int nr_cpus, int page_size,
>  				 unsigned int *ports, bool use_fifos,
> -				 unsigned long long trace_id);
> +				 unsigned long long trace_id,
> +				 unsigned int tsync_proto,
> +				 unsigned int tsync_port);
>  int tracecmd_msg_recv_trace_resp(struct tracecmd_msg_handle *msg_handle,
>  				 int *nr_cpus, int *page_size,
>  				 unsigned int **ports, bool *use_fifos,
> -				 unsigned long long *trace_id);
> +				 unsigned long long *trace_id,
> +				 unsigned int *tsync_proto,
> +				 unsigned int *tsync_port);
> +
> +int tracecmd_msg_send_time_sync(struct tracecmd_msg_handle *msg_handle,
> +				unsigned int sync_protocol,
> +				unsigned int sync_msg_id,
> +				unsigned int payload_size, char *payload);
> +int tracecmd_msg_recv_time_sync(struct tracecmd_msg_handle *msg_handle,
> +				unsigned int *sync_protocol,
> +				unsigned int *sync_msg_id,
> +				unsigned int *payload_size, char **payload);
> +
>  /* --- ftrace instances --- */
>  
>  struct tracecmd_instance;
> @@ -407,6 +426,38 @@ int tracecmd_iterate_raw_events(struct tep_handle *tep,
>  				void *callback_context);
>  
>  
> +/* --- Timestamp synchronization --- */
> +
> +enum{
> +	TRACECMD_TIME_SYNC_PROTO_NONE	= 0,
> +};
> +enum{
> +	TRACECMD_TIME_SYNC_CMD_PROBE	= 1,
> +	TRACECMD_TIME_SYNC_CMD_STOP	= 2,
> +};
> +
> +#define TRACECMD_TIME_SYNC_PROTO_PTP_WEIGHT	10
> +
> +struct tracecmd_time_sync {
> +	unsigned int			sync_proto;
> +	int				loop_interval;
> +	pthread_mutex_t			lock;
> +	pthread_cond_t			cond;
> +	char				*clock_str;
> +	struct tracecmd_msg_handle	*msg_handle;
> +	void				*context;
> +};
> +
> +void tracecmd_tsync_init(void);
> +int tracecmd_tsync_proto_getall(char **proto_mask, int *words);
> +unsigned int tracecmd_tsync_proto_select(char *proto_mask, int words);
> +bool tsync_proto_is_supported(unsigned int proto_id);
> +void tracecmd_tsync_with_host(struct tracecmd_time_sync *tsync);
> +void tracecmd_tsync_with_guest(struct tracecmd_time_sync *tsync);
> +int tracecmd_tsync_get_offsets(struct tracecmd_time_sync *tsync,
> +				int *count,
> +				long long **ts, long long **offsets);
> +void tracecmd_tsync_free(struct tracecmd_time_sync *tsync);
>  
>  /* --- Plugin handling --- */
>  extern struct tep_plugin_option trace_ftrace_options[];
> diff --git a/lib/trace-cmd/Makefile b/lib/trace-cmd/Makefile
> index 18c7013..6221b36 100644
> --- a/lib/trace-cmd/Makefile
> +++ b/lib/trace-cmd/Makefile
> @@ -16,6 +16,7 @@ OBJS += trace-util.o
>  OBJS += trace-instance.o
>  OBJS += trace-filter-hash.o
>  OBJS += trace-msg.o
> +OBJS += trace-timesync.o
>  
>  # Additional util objects
>  OBJS += trace-blk-hack.o
> diff --git a/lib/trace-cmd/include/trace-tsync-local.h b/lib/trace-cmd/include/trace-tsync-local.h
> new file mode 100644
> index 0000000..511c838
> --- /dev/null
> +++ b/lib/trace-cmd/include/trace-tsync-local.h
> @@ -0,0 +1,38 @@
> +/* SPDX-License-Identifier: LGPL-2.1 */
> +/*
> + * Copyright (C) 2019, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
> + *
> + */
> +#ifndef _TRACE_TSYNC_LOCAL_H
> +#define _TRACE_TSYNC_LOCAL_H
> +
> +#include <stdbool.h>
> +
> +struct clock_sync_context {
> +	void				*proto_data;	/* time sync protocol specific data */
> +	bool				server;		/* server or guest time sync role */

Let's call this "is_server" as it is a boolean value. "server" looks
like it should be a pointer or something.

> +	struct tracecmd_instance	*vinst;		/* ftrace buffer, used for time sync events */

As this is part of a structure and not a global that would interfere
with other name spaces, I think it should be called "instance", as I
had no idea what "vinst" was when looking at it below. Let's be
consistent and call struct tracecmd_instance "instance" when we can.
That way we know exactly what it is by looking at the name.

> +
> +	/* Arrays with calculated time offsets at given time */
> +	int				sync_size;	/* Allocated size of sync_ts and sync_offsets */
> +	int				sync_count;	/* Number of elements in sync_ts and sync_offsets */
> +	long long			*sync_ts;
> +	long long			*sync_offsets;
> +
> +	/* Identifiers of local and remote time sync peers: cid and port */
> +	unsigned int			local_cid;
> +	unsigned int			local_port;
> +	unsigned int			remote_cid;
> +	unsigned int			remote_port;
> +};
> +
> +int tracecmd_tsync_proto_register(unsigned int proto_id, int weight,
> +				int (*init)(struct tracecmd_time_sync *),
> +				int (*free)(struct tracecmd_time_sync *),
> +				int (*calc)(struct tracecmd_time_sync *,
> +					    long long *, long long *));
> +int tracecmd_tsync_proto_unregister(unsigned int proto_id);
> +
> +int ptp_clock_sync_register(void);
> +
> +#endif /* _TRACE_TSYNC_LOCAL_H */
> diff --git a/lib/trace-cmd/trace-msg.c b/lib/trace-cmd/trace-msg.c
> index a34297f..551b9a0 100644
> --- a/lib/trace-cmd/trace-msg.c
> +++ b/lib/trace-cmd/trace-msg.c
> @@ -28,6 +28,8 @@
>  
>  typedef __u32 u32;
>  typedef __be32 be32;
> +typedef __u64 u64;
> +typedef __s64 s64;
>  
>  static inline void dprint(const char *fmt, ...)
>  {
> @@ -60,9 +62,20 @@ struct tracecmd_msg_rinit {
>  	be32 cpus;
>  } __attribute__((packed));
>  
> +#define TRACE_REQ_PARAM_SIZE  (2 * sizeof(int))
> +enum trace_req_params {
> +	TRACE_REQUEST_ARGS,
> +	TRACE_REQUEST_TSYNC_PROTOS,
> +};
> +
> +struct tracecmd_msg_trace_req_param {
> +	int id;
> +	int length;
> +	char *value;
> +};
> +
>  struct tracecmd_msg_trace_req {
>  	be32 flags;
> -	be32 argc;
>  	u64 trace_id;
>  } __attribute__((packed));
>  
> @@ -71,6 +84,13 @@ struct tracecmd_msg_trace_resp {
>  	be32 cpus;
>  	be32 page_size;
>  	u64 trace_id;
> +	be32 tsync_proto;
> +	be32 tsync_port;
> +} __attribute__((packed));
> +
> +struct tracecmd_msg_tsync {
> +	be32 sync_protocol;
> +	be32 sync_msg_id;
>  } __attribute__((packed));
>  
>  struct tracecmd_msg_header {
> @@ -88,7 +108,8 @@ struct tracecmd_msg_header {
>  	C(NOT_SUPP,	5,	0),					\
>  	C(TRACE_REQ,	6,	sizeof(struct tracecmd_msg_trace_req)),	\
>  	C(TRACE_RESP,	7,	sizeof(struct tracecmd_msg_trace_resp)),\
> -	C(CLOSE_RESP,	8,	0),
> +	C(CLOSE_RESP,	8,	0),					\
> +	C(TIME_SYNC,	9,	sizeof(struct tracecmd_msg_tsync)),
>  
>  #undef C
>  #define C(a,b,c)	MSG_##a = b
> @@ -122,6 +143,7 @@ struct tracecmd_msg {
>  		struct tracecmd_msg_rinit	rinit;
>  		struct tracecmd_msg_trace_req	trace_req;
>  		struct tracecmd_msg_trace_resp	trace_resp;
> +		struct tracecmd_msg_tsync	tsync;
>  	};
>  	char					*buf;
>  } __attribute__((packed));
> @@ -264,6 +286,17 @@ static int tracecmd_msg_send(int fd, struct tracecmd_msg *msg)
>  	return ret;
>  }
>  
> +static int msg_send_nofree(int fd, struct tracecmd_msg *msg)
> +{
> +	int ret = 0;
> +
> +	ret = msg_write(fd, msg);
> +	if (ret < 0)
> +		ret = -ECOMM;
> +
> +	return ret;
> +}
> +
>  static int msg_read(int fd, void *buf, u32 size, int *n)
>  {
>  	ssize_t r;
> @@ -813,82 +846,142 @@ int tracecmd_msg_wait_close_resp(struct tracecmd_msg_handle *msg_handle)
>  	return tracecmd_msg_wait_for_cmd(msg_handle, MSG_CLOSE_RESP);
>  }
>  
> -static int make_trace_req(struct tracecmd_msg *msg, int argc, char **argv,
> -			  bool use_fifos, unsigned long long trace_id)
> +static int make_trace_req_protos(char **buf, int *size,
> +				 int protos_size, char *tsync_protos)
> +{
> +	size_t buf_size = 0;

Why initialize buf_size to zero, when you set it below in the first
instruction?

> +	char *nbuf;
> +	char *p;
> +
> +	buf_size = TRACE_REQ_PARAM_SIZE + protos_size;
> +	nbuf = realloc(*buf, *size + buf_size);
> +	if (!nbuf)
> +		return -1;
> +
> +	p = nbuf + *size;
> +	memset(p, 0, buf_size);
> +
> +	*(unsigned int *)p = htonl(TRACE_REQUEST_TSYNC_PROTOS);
> +	p += sizeof(int);
> +	*(unsigned int *)p = htonl(protos_size);
> +	p += sizeof(int);
> +
> +	memcpy(p, tsync_protos, protos_size);
> +
> +	*size += buf_size;
> +	*buf = nbuf;
> +	return 0;
> +}
> +
> +static int make_trace_req_args(char **buf, int *size, int argc, char **argv)
>  {
>  	size_t args_size = 0;
> +	size_t buf_size = 0;

Same here. args_size and buf_size are not used before they are assigned.

> +	char *nbuf;
>  	char *p;
>  	int i;
>  
> +	args_size = sizeof(int);
>  	for (i = 0; i < argc; i++)
>  		args_size += strlen(argv[i]) + 1;
>  
> -	msg->hdr.size = htonl(ntohl(msg->hdr.size) + args_size);
> -	msg->trace_req.flags = use_fifos ? htonl(MSG_TRACE_USE_FIFOS) : htonl(0);
> -	msg->trace_req.argc = htonl(argc);
> -	msg->trace_req.trace_id = htonll(trace_id);
> -	msg->buf = calloc(args_size, 1);
> -	if (!msg->buf)
> -		return -ENOMEM;
> +	buf_size = TRACE_REQ_PARAM_SIZE + args_size;
> +	nbuf = realloc(*buf, *size + buf_size);
> +	if (!nbuf)
> +		return -1;
> +
> +	p = nbuf + *size;
> +	memset(p, 0, buf_size);
> +
> +	*(unsigned int *)p = htonl(TRACE_REQUEST_ARGS);
> +	p += sizeof(int);
> +	*(unsigned int *)p = htonl(args_size);
> +	p += sizeof(int);
>  
> -	p = msg->buf;
> +	*(unsigned int *)p = htonl(argc);
> +	p += sizeof(int);
>  	for (i = 0; i < argc; i++)
>  		p = stpcpy(p, argv[i]) + 1;
>  
> +	*size += buf_size;
> +	*buf = nbuf;
> +	return 0;
> +}
> +

[..]

> +
> +
> +#define PROTO_MASK_SIZE (sizeof(char))

I'm thinking that declaring a mask the size of 1 is a bit overkill.

> +/**
> + * tracecmd_tsync_proto_select - Select time sync protocol, to be used for
> + *		timestamp synchronization with a peer
> + *
> + * @proto_mask: bitmask array of time sync protocols, supported by the peer
> + * @words: size of the @protos array
> + *
> + * Retuns Id of a time sync protocol, that can be used with the peer, or 0
> + *	  in case there is no match with supported protocols
> + */
> +unsigned int tracecmd_tsync_proto_select(char *proto_mask, int words)

Probably should just call it "length", as words usually means "int" or
"long".

> +{
> +	struct tsync_proto *selected = NULL;
> +	struct tsync_proto *proto;
> +	int word;
> +	int id;
> +
> +	for (word = 0; word < words; word++) {
> +		for (proto = tsync_proto_list; proto; proto = proto->next) {
> +			if (proto->proto_id < word * PROTO_MASK_SIZE)

Then we can remove the multiplier here.

Also, if the tsync_proto_list is sorted, we could optimize this. But
that's an optimization for another day, as we currently only have a
single proto.


> +				continue;
> +
> +			id = proto->proto_id - word * PROTO_MASK_SIZE;
> +			if (id >= PROTO_MASK_SIZE)
> +				continue;
> +
> +			if ((1 << id) & proto_mask[word]) {
> +				if (selected) {
> +					if (selected->weight < proto->weight)
> +						selected = proto;
> +				} else
> +					selected = proto;
> +			}
> +		}
> +	}
> +
> +	if (selected)
> +		return selected->proto_id;
> +
> +	return 0;
> +}
> +

[..]

> +static struct tracecmd_instance *
> +clock_synch_create_instance(const char *clock, unsigned int cid)
> +{
> +	struct tracecmd_instance *vinst;

Let's call this "instance".

> +	char inst_name[256];
> +
> +	snprintf(inst_name, 256, "clock_synch-%d", cid);
> +
> +	vinst = tracecmd_alloc_instance(inst_name);
> +	if (!vinst)
> +		return NULL;
> +
> +	tracecmd_make_instance(vinst);
> +	tracecmd_write_instance_file(vinst, "trace", "\0", NULL);
> +	tracecmd_alloc_instance_clock(vinst, clock);
> +	tracecmd_set_clock(vinst, NULL);
> +	return vinst;
> +}
> +

[..]

> +/**
> + * tracecmd_tsync_free - Free time sync context, allocated by
> + *		tracecmd_tsync_with_host() or tracecmd_tsync_with_guest() APIs
> + *
> + * @tsync: Pointer to time sync context
> + *
> + */
> +void tracecmd_tsync_free(struct tracecmd_time_sync *tsync)
> +{
> +	struct clock_sync_context *tsync_context;
> +	struct tsync_proto *proto;
> +
> +	if (!tsync->context)
> +		return;
> +	tsync_context = (struct clock_sync_context *)tsync->context;
> +
> +	proto = tsync_proto_find(tsync->sync_proto);
> +	if (proto && proto->clock_sync_free)
> +		proto->clock_sync_free(tsync);
> +
> +	clock_synch_delete_instance(tsync_context->vinst);
> +	tsync_context->vinst = NULL;
> +
> +	free(tsync_context->sync_ts);
> +	free(tsync_context->sync_offsets);
> +	tsync_context->sync_ts = NULL;
> +	tsync_context->sync_offsets = NULL;
> +	tsync_context->sync_count = 0;
> +	tsync_context->sync_size = 0;
> +	pthread_mutex_destroy(&tsync->lock);
> +	pthread_cond_destroy(&tsync->cond);
> +	free(tsync->clock_str);

I would think we would want a free(tsync) here. As the name of the
function suggests.

> +}
> +
> +int tracecmd_tsync_send(struct tracecmd_time_sync *tsync,
> +				  struct tsync_proto *proto)
> +{
> +	long long timestamp = 0;
> +	long long offset = 0;
> +	int ret;
> +
> +	ret = proto->clock_sync_calc(tsync, &offset, &timestamp);
> +
> +	return ret;
> +}
> +



> +++ b/tracecmd/trace-tsync.c
> @@ -0,0 +1,271 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019, VMware, Tzvetomir Stoyanov <tz.stoyanov@gmail.com>
> + *
> + */
> +#include <stdlib.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <sys/socket.h>
> +#include <unistd.h>
> +#include <linux/vm_sockets.h>
> +#include <pthread.h>
> +
> +#include "trace-local.h"
> +#include "trace-msg.h"
> +
> +static int get_first_cpu(cpu_set_t **pin_mask, size_t *m_size)
> +{
> +	int cpus = tracecmd_count_cpus();
> +	cpu_set_t *cpu_mask;
> +	int mask_size;
> +	int i;
> +
> +	cpu_mask = CPU_ALLOC(cpus);
> +	*pin_mask = CPU_ALLOC(cpus);
> +	if (!cpu_mask || !*pin_mask || 1)
> +		goto error;
> +
> +	mask_size = CPU_ALLOC_SIZE(cpus);
> +	CPU_ZERO_S(mask_size, cpu_mask);
> +	CPU_ZERO_S(mask_size, *pin_mask);
> +
> +	if (sched_getaffinity(0, mask_size, cpu_mask) == -1)
> +		goto error;
> +
> +	for (i = 0; i < cpus; i++) {
> +		if (CPU_ISSET_S(i, mask_size, cpu_mask)) {
> +			CPU_SET_S(i, mask_size, *pin_mask);
> +			break;
> +		}
> +	}
> +
> +	if (CPU_COUNT_S(mask_size, *pin_mask) < 1)
> +		goto error;
> +
> +	CPU_FREE(cpu_mask);
> +	*m_size = mask_size;
> +	return 0;
> +
> +error:
> +	if (cpu_mask)
> +		CPU_FREE(cpu_mask);
> +	if (*pin_mask)
> +		CPU_FREE(*pin_mask);
> +	*pin_mask = NULL;
> +	*m_size = 0;
> +	return -1;
> +}
> +
> +static void *tsync_host_thread(void *data)
> +{
> +	struct tracecmd_time_sync *tsync = NULL;
> +
> +	tsync = (struct tracecmd_time_sync *)data;
> +
> +	tracecmd_tsync_with_guest(tsync);
> +
> +	tracecmd_msg_handle_close(tsync->msg_handle);
> +	tsync->msg_handle = NULL;
> +
> +	pthread_exit(0);
> +}
> +
> +int tracecmd_host_tsync(struct buffer_instance *instance,
> +			 unsigned int tsync_port)
> +{
> +	struct tracecmd_msg_handle *msg_handle = NULL;
> +	cpu_set_t *pin_mask = NULL;
> +	pthread_attr_t attrib;
> +	size_t mask_size = 0;
> +	int ret;
> +	int fd;
> +
> +	if (!instance->tsync.sync_proto)
> +		return -1;
> +
> +	fd = trace_open_vsock(instance->cid, tsync_port);
> +	if (fd < 0) {
> +		ret = -1;
> +		goto out;
> +	}
> +	msg_handle = tracecmd_msg_handle_alloc(fd, 0);
> +	if (!msg_handle) {
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	instance->tsync.msg_handle = msg_handle;
> +	if (tracecmd_get_instance_clock(top_instance.ftrace))
> +		instance->tsync.clock_str = strdup(tracecmd_get_instance_clock(top_instance.ftrace));
> +	pthread_mutex_init(&instance->tsync.lock, NULL);
> +	pthread_cond_init(&instance->tsync.cond, NULL);
> +
> +	pthread_attr_init(&attrib);
> +	pthread_attr_setdetachstate(&attrib, PTHREAD_CREATE_JOINABLE);
> +	if (!get_first_cpu(&pin_mask, &mask_size))
> +		pthread_attr_setaffinity_np(&attrib, mask_size, pin_mask);
> +
> +	ret = pthread_create(&instance->tsync_thread, &attrib,
> +			     tsync_host_thread, &instance->tsync);
> +	if (!ret)
> +		instance->tsync_thread_running = true;
> +	if (pin_mask)
> +		CPU_FREE(pin_mask);
> +	pthread_attr_destroy(&attrib);
> +
> +out:
> +	if (ret) {
> +		if (msg_handle)
> +			tracecmd_msg_handle_close(msg_handle);
> +	}
> +
> +	return ret;
> +}
> +
> +static void write_guest_time_shift(struct buffer_instance *instance)
> +{
> +	struct tracecmd_output *handle;
> +	struct iovec vector[4];
> +	long long *offsets;
> +	long long *ts;
> +	char *file;
> +	int count;
> +	int ret;
> +	int fd;
> +
> +	ret = tracecmd_tsync_get_offsets(&instance->tsync, &count, &ts, &offsets);
> +	if (ret < 0 || !count || !ts || !offsets)
> +		return;
> +
> +	file = trace_get_guest_file(TRACE_FILENAME,
> +			      tracecmd_get_instance_name(instance->ftrace));
> +	fd = open(file, O_RDWR);
> +	if (fd < 0)
> +		die("error opening %s", file);
> +	free(file);
> +	handle = tracecmd_get_output_handle_fd(fd);
> +	vector[0].iov_len = 8;
> +	vector[0].iov_base = &top_instance.trace_id;
> +	vector[1].iov_len = 4;
> +	vector[1].iov_base = &count;
> +	vector[2].iov_len = 8 * count;
> +	vector[2].iov_base = ts;
> +	vector[3].iov_len = 8 * count;
> +	vector[3].iov_base = offsets;
> +	tracecmd_add_option_v(handle, TRACECMD_OPTION_TIME_SHIFT, vector, 4);
> +	tracecmd_append_options(handle);
> +	tracecmd_output_close(handle);
> +#ifdef TSYNC_DEBUG
> +	if (count > 1)
> +		printf("Got %d timestamp synch samples for guest %s in %lld ns trace\n\r",
> +			count, tracecmd_get_instance_name(instance->ftrace),
> +			ts[count - 1] - ts[0]);
> +#endif
> +}
> +
> +void tracecmd_host_tsync_complete(struct buffer_instance *instance)
> +{
> +	if (!instance->tsync_thread_running)
> +		return;
> +

Probably should add a comment to what is going on here ;-)

> +	pthread_mutex_lock(&instance->tsync.lock);
> +	pthread_cond_signal(&instance->tsync.cond);
> +	pthread_mutex_unlock(&instance->tsync.lock);
> +	pthread_join(instance->tsync_thread, NULL);
> +	write_guest_time_shift(instance);
> +	tracecmd_tsync_free(&instance->tsync);
> +}
> +
> +static void *tsync_agent_thread(void *data)
> +{
> +	struct tracecmd_time_sync *tsync = NULL;
> +	int sd;
> +
> +	tsync = (struct tracecmd_time_sync *)data;
> +
> +	while (true) {
> +		sd = accept(tsync->msg_handle->fd, NULL, NULL);
> +		if (sd < 0) {
> +			if (errno == EINTR)
> +				continue;
> +			goto out;
> +		}
> +		break;
> +	}
> +	close(tsync->msg_handle->fd);
> +	tsync->msg_handle->fd = sd;
> +
> +	tracecmd_tsync_with_host(tsync);
> +
> +out:
> +	tracecmd_msg_handle_close(tsync->msg_handle);
> +	tracecmd_tsync_free(tsync);
> +	free(tsync);
> +	close(sd);
> +
> +	pthread_exit(0);
> +}
> +
> +unsigned int tracecmd_guest_tsync(char *tsync_protos,
> +				  unsigned int tsync_protos_size, char *clock,
> +				  unsigned int *tsync_port, pthread_t *thr_id)
> +{
> +	struct tracecmd_time_sync *tsync = NULL;
> +	cpu_set_t *pin_mask = NULL;
> +	pthread_attr_t attrib;
> +	size_t mask_size = 0;
> +	unsigned int proto;
> +	int ret;
> +	int fd;
> +
> +	fd = -1;
> +	proto = tracecmd_tsync_proto_select(tsync_protos, tsync_protos_size);
> +	if (!proto)
> +		return 0;
> +#ifdef VSOCK
> +	fd = trace_make_vsock(VMADDR_PORT_ANY);
> +	if (fd < 0)
> +		goto error;
> +
> +	ret = trace_get_vsock_port(fd, tsync_port);
> +	if (ret < 0)
> +		goto error;
> +#else
> +	return 0;

If we have no synchronization support, shouldn't this return an error?

> +#endif
> +
> +	tsync = calloc(1, sizeof(struct tracecmd_time_sync));
> +	tsync->msg_handle = tracecmd_msg_handle_alloc(fd, 0);
> +	if (clock)
> +		tsync->clock_str = strdup(clock);
> +
> +	pthread_attr_init(&attrib);
> +	tsync->sync_proto = proto;
> +	pthread_attr_setdetachstate(&attrib, PTHREAD_CREATE_JOINABLE);
> +	if (!get_first_cpu(&pin_mask, &mask_size))
> +		pthread_attr_setaffinity_np(&attrib, mask_size, pin_mask);
> +
> +	ret = pthread_create(thr_id, &attrib, tsync_agent_thread, tsync);
> +
> +	if (pin_mask)
> +		CPU_FREE(pin_mask);
> +	pthread_attr_destroy(&attrib);
> +
> +	if (ret)
> +		goto error;
> +
> +	return proto;
> +
> +error:
> +	if (tsync) {
> +		if (tsync->msg_handle)
> +			tracecmd_msg_handle_close(tsync->msg_handle);
> +		if (tsync->clock_str)
> +			free(tsync->clock_str);

You don't need the if statement. free() can take a NULL pointer.

Anyway, it's looking good. I like a lot of what you did. Especially
with the helpers you created.

I still need to take a deeper look at this and the following patches.
I'm thinking that this patch could possibly be broken up into two or
three patches. One patch to create the protocol, another one or two
that use the protocol.

Although we are very close to getting this in, I've been thinking more
that we should release 2.9, without the time sync. We may need to just
up the protocol when we implement the synchronization.

I'll look more at this on Monday.

Cheers!

-- Steve



> +		free(tsync);
> +	}
> +	if (fd > 0)
> +		close(fd);
> +	return 0;
> +}
> diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
> index 05ec021..9fa61e1 100644
> --- a/tracecmd/trace-usage.c
> +++ b/tracecmd/trace-usage.c
> @@ -60,6 +60,10 @@ static struct usage_help usage_help[] = {
>  		"          --no-filter include trace-cmd threads in the trace\n"
>  		"          --proc-map save the traced processes address map into the trace.dat file\n"
>  		"          --user execute the specified [command ...] as given user\n"
> +		"          --tsync-interval set the loop interval, in ms, for timestamps synchronization with guests:"
> +		"               If a negative number is specified, timestamps synchronization is disabled"
> +		"               If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
> +		"                                                         at the beginnig and at the end of the trace\n"
>  	},
>  	{
>  		"start",

Re: [PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file

[Tzvetomir Stoyanov]

On Fri, Dec 20, 2019 at 10:04 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Fri, 13 Dec 2019 17:30:21 +0200
> "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
>
> > The ID of the current tracing session is stored in the trace.dat file.
> > A new file option is introduced:
> >       TRACECMD_OPTION_TRACEID
> > The data is stored in the file as NULL terminated string:
> >       "\nTraceID: %llu\n"
>
> If the trace ID is just a 64 bit number, why is it stored in the file
> as a string?
>

The only reason for this is to avoid endian long long conversions,
and to simplify reading of trace.dat file, for debug purposes.

> -- Steve
>
>
> > A new libtracecmd API is introduced, to get the ID when the trace.dat file is read:
> >       unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
> >
> > Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
> > ---
> >  include/trace-cmd/trace-cmd.h |  2 ++
> >  lib/trace-cmd/trace-input.c   | 25 +++++++++++++++++++++++++
> >  tracecmd/trace-record.c       | 15 +++++++++++++++
> >  3 files changed, 42 insertions(+)
> >
> > diff --git a/include/trace-cmd/trace-cmd.h b/include/trace-cmd/trace-cmd.h
> > index ad69313..6cc2913 100644
> > --- a/include/trace-cmd/trace-cmd.h
> > +++ b/include/trace-cmd/trace-cmd.h
> > @@ -86,6 +86,7 @@ enum {
> >       TRACECMD_OPTION_CPUCOUNT,
> >       TRACECMD_OPTION_VERSION,
> >       TRACECMD_OPTION_PROCMAPS,
> > +     TRACECMD_OPTION_TRACEID,
> >  };
> >
> >  enum {
> > @@ -128,6 +129,7 @@ int tracecmd_copy_headers(struct tracecmd_input *handle, int fd);
> >  void tracecmd_set_flag(struct tracecmd_input *handle, int flag);
> >  void tracecmd_clear_flag(struct tracecmd_input *handle, int flag);
> >  unsigned long tracecmd_get_flags(struct tracecmd_input *handle);
> > +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle);
> >
> >  void tracecmd_parse_trace_clock(struct tracecmd_input *handle, char *file, int size);
> >
> > diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
> > index 91362f3..40d9825 100644
> > --- a/lib/trace-cmd/trace-input.c
> > +++ b/lib/trace-cmd/trace-input.c
> > @@ -79,6 +79,7 @@ struct tracecmd_input {
> >       struct tep_plugin_list  *plugin_list;
> >       struct tracecmd_input   *parent;
> >       unsigned long           flags;
> > +     unsigned long long      trace_id;
> >       int                     fd;
> >       int                     long_size;
> >       int                     page_size;
> > @@ -2169,6 +2170,15 @@ static void procmap_free(struct pid_addr_maps *maps)
> >       free(maps);
> >  }
> >
> > +static int trace_traceid_load(struct tracecmd_input *handle, char *buf)
> > +{
> > +
> > +     if (sscanf(buf, "%*s %llu", &handle->trace_id) == 1)
> > +             return 0;
> > +
> > +     return -1;
> > +}
> > +
> >  #define STR_PROCMAP_LINE_MAX (PATH_MAX+22)
> >  static int trace_pid_map_load(struct tracecmd_input *handle, char *buf)
> >  {
> > @@ -2406,6 +2416,10 @@ static int handle_options(struct tracecmd_input *handle)
> >                       if (buf[size-1] == '\0')
> >                               trace_pid_map_load(handle, buf);
> >                       break;
> > +             case TRACECMD_OPTION_TRACEID:
> > +                     if (buf[size-1] == '\0')
> > +                             trace_traceid_load(handle, buf);
> > +                     break;
> >               default:
> >                       warning("unknown option %d", option);
> >                       break;
> > @@ -3507,3 +3521,14 @@ void tracecmd_set_show_data_func(struct tracecmd_input *handle,
> >  {
> >       handle->show_data_func = func;
> >  }
> > +
> > +/**
> > + * tracecmd_get_traceid - get the trace id of the session
> > + * @handle: input handle for the trace.dat file
> > + *
> > + * Returns the trace id, written in the trace file
> > + */
> > +unsigned long long tracecmd_get_traceid(struct tracecmd_input *handle)
> > +{
> > +     return handle->trace_id;
> > +}
> > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
> > index 7089f7b..b65aeb2 100644
> > --- a/tracecmd/trace-record.c
> > +++ b/tracecmd/trace-record.c
> > @@ -3714,6 +3714,19 @@ add_pid_maps(struct tracecmd_output *handle, struct buffer_instance *instance)
> >       trace_seq_destroy(&s);
> >  }
> >
> > +static void
> > +add_trace_id(struct tracecmd_output *handle, struct buffer_instance *instance)
> > +{
> > +     char *str = NULL;
> > +     int len;
> > +
> > +     len = asprintf(&str, "\nTraceID: %llu\n", instance->trace_id);
> > +     if (len < 1)
> > +             return;
> > +     tracecmd_add_option(handle, TRACECMD_OPTION_TRACEID, len + 1, str);
> > +     free(str);
> > +}
> > +
> >  static void
> >  add_buffer_stat(struct tracecmd_output *handle, struct buffer_instance *instance)
> >  {
> > @@ -3817,6 +3830,8 @@ static void add_options(struct tracecmd_output *handle, struct common_record_con
> >       add_option_hooks(handle);
> >       add_uname(handle);
> >       add_version(handle);
> > +     if (!no_top_instance())
> > +             add_trace_id(handle, &top_instance);
> >  }
> >
> >  static void write_guest_file(struct buffer_instance *instance)
>


-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file

[Tzvetomir Stoyanov]

On Fri, Dec 20, 2019 at 10:52 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Fri, 13 Dec 2019 17:30:24 +0200
> "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
>
> > New trace.dat option is introduced: TRACECMD_OPTION_GUEST.
> > Written in the host's trace.dat file, it contains information about
> > guests, traced at the same time: guest trace ID, number of VCPUs and
> > PIDs of the host tasks, running those VCPU. The data is stored in
> > the file as NULL terminated string:
> >       "Guest %s %llu %d\n" -> guest name, number of VCPUs
> >       "%d %d\n" -> VCPU, PID of host task
> >       .....
> >       "%d %d\n" -> VCPU, PID of host task
>
> Why is this a string, and not a structure?

To avoid endian long long conversions, and to simplify reading of
trace.dat file, for debug purposes.
I would suggest to keep it text, for two reasons:
 - this information is not huge, the binary format will not reduce the
size of the trace.dat file significantly.
 - it is very useful to be possible to check what guest information is
stored in the file, using simple cat

We could think of implementing some stand alone trace.dat file reader,
to extract and display that meta data information.

>
> -- Steve



-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v18 04/18] trace-cmd: Add new library APIs for ftrace instances.

[Tzvetomir Stoyanov]

On Sat, Dec 21, 2019 at 5:03 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Fri, 13 Dec 2019 17:30:15 +0200
> "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
>
> > +/**
> > + * tracecmd_get_instance_file - return the path to a instance file
> > + * @instance: buffer instance for the file, can be NULL for the top instance
> > + * @file: name of file to return
> > + *
> > + * Returns the path name of the @file for the given @instance
> > + *
> > + * Must use tracecmd_put_tracing_file() to free the returned string
> > + */
> > +char *
> > +tracecmd_get_instance_file(struct tracecmd_instance *instance, const char *file)
> > +{
> > +     char *path;
> > +     char *buf;
> > +     int ret;
> > +
> > +     if (instance && instance->name) {
> > +             ret = asprintf(&buf, "instances/%s/%s", instance->name, file);
> > +             if (ret < 0)
> > +                     die("Failed to allocate name for %s/%s", instance->name, file);
> > +             path = tracecmd_get_tracing_file(buf);
> > +             free(buf);
> > +     } else
> > +             path = tracecmd_get_tracing_file(file);
> > +
> > +     return path;
> > +}
> > +
> > +/**
> > + * tracecmd_get_instance_file - return the path to a instance file
> > + * @instance: buffer instance for the file, can be NULL for the top instance
> > + * @file: name of file to return
> > + *
> > + * Returns the path name of the @file for the given @instance
> > + *
> > + * Must use tracecmd_put_tracing_file() to free the returned string
>
> The above is a cut and paste of tracecmd_get_instance_file, not of the
> instance_dir.
>
> > + */
> > +char *tracecmd_get_instance_dir(struct tracecmd_instance *instance)
> > +{
> > +     char *buf;
> > +     char *path;
> > +     int ret;
> > +
> > +     if (instance->name) {
> > +             ret = asprintf(&buf, "instances/%s", instance->name);
> > +             if (ret < 0)
> > +                     die("Failed to allocate for instance %s", instance->name);
> > +             path = tracecmd_get_tracing_file(buf);
> > +             free(buf);
> > +     } else
> > +             path = tracecmd_find_tracing_dir();
> > +
> > +     return path;
> > +}
> > +
> > +/**
> > + * tracecmd_write_instance_file - Write in trace file of specific instance
> > + * @instance: buffer instance for the file, can be NULL for the top instance
> > + * @file: name of the file
> > + * @str: Nul terminated string, that will be written in the file
> > + * @type: Nul terminated string, describing the current write operation
> > + *     Used for logging purposes
> > + *
> > + * Returns the number of written bytes, or -1 in case of an error
> > + */
> > +int tracecmd_write_instance_file(struct tracecmd_instance *instance,
> > +                              const char *file, const char *str,
> > +                              const char *type)
>
> I think we should get rid of the type and move the logic that needs it
> to the callers.
>
>
> > +{
> > +     struct stat st;
> > +     char *path;
> > +     int ret;
> > +
> > +     path = tracecmd_get_instance_file(instance, file);
> > +     ret = stat(path, &st);
> > +     if (ret == 0)
> > +             ret = tracecmd_write_file(path, str, type);
> > +     tracecmd_put_tracing_file(path);
> > +
> > +     return ret;
> > +}
> > +
>
> [..]
>
> > +/*
> > + * tracecmd_write_file - Write in trace file
> > + * @file: Full name of the trace file.
> > + * @str: Null terminated string, that will be written in the file.
> > + * @type: Null terminated string, describing the current write operation.
> > + *     Used for logging purposes.
> > + *
> > + * Returns the number of written bytes, or -1 in case of an error
> > + */
> > +int tracecmd_write_file(const char *file, const char *str, const char *type)
> > +{
> > +     char buf[BUFSIZ];
> > +     int ret;
> > +     int fd;
> > +
> > +     fd = open(file, O_WRONLY | O_TRUNC);
> > +     if (fd < 0)
> > +             die("opening to '%s'", file);
> > +     ret = write(fd, str, strlen(str));
> > +     close(fd);
> > +     if (ret < 0 && type) {
> > +             /* write failed */
> > +             fd = open(file, O_RDONLY);
> > +             if (fd < 0)
> > +                     die("writing to '%s'", file);
> > +             /* the filter has the error */
> > +             while ((ret = read(fd, buf, BUFSIZ)) > 0)
> > +                     fprintf(stderr, "%.*s", ret, buf);
> > +             die("Failed %s of %s\n", type, file);
>
> Yeah, the above needs to be moved to the upper layers. It even has a
> comment about "the filter has the error". That's reference to the
> filter file of trace events, which is the only file that really does
> that.
>
> -- Steve
>

These new instance APIs are going to be part of the new libtracefs,
I'll remove this patch
from the series, when the libtracefs code is merged.

> > +             close(fd);
> > +     }
> > +     return ret;
> > +}
> >



-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file

[Steven Rostedt]

On Mon, 6 Jan 2020 16:43:03 +0200
Tzvetomir Stoyanov <tz.stoyanov@gmail.com> wrote:

> We could think of implementing some stand alone trace.dat file reader,
> to extract and display that meta data information.

This is the right thing to do. I've actually started doing this here
and there, but mostly via the trace-cmd report options.

But we should have a full parser of the trace.dat file. Could be an
option for trace-cmd. "trace-cmd dump"?

-- Steve

Re: [PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization

[Tzvetomir Stoyanov]

On Sat, Dec 21, 2019 at 6:48 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
 [ .. ]
> > +#define PROTO_MASK_SIZE (sizeof(char))
>
> I'm thinking that declaring a mask the size of 1 is a bit overkill.
>
This define is a leftover from the previous implementation of this
bitmask, where
the size was 4 bytes. It was very easy to switch to 1 byte using the
define, that's
why I would prefer to keep it - in case we decide to change the size again.
The code below is written with the assumption that the size could be
more than 1 byte.

[ .. ]
> > + */
> > +void tracecmd_tsync_free(struct tracecmd_time_sync *tsync)
> > +{
> > +     struct clock_sync_context *tsync_context;
> > +     struct tsync_proto *proto;
> > +
> > +     if (!tsync->context)
> > +             return;
> > +     tsync_context = (struct clock_sync_context *)tsync->context;
> > +
> > +     proto = tsync_proto_find(tsync->sync_proto);
> > +     if (proto && proto->clock_sync_free)
> > +             proto->clock_sync_free(tsync);
> > +
> > +     clock_synch_delete_instance(tsync_context->vinst);
> > +     tsync_context->vinst = NULL;
> > +
> > +     free(tsync_context->sync_ts);
> > +     free(tsync_context->sync_offsets);
> > +     tsync_context->sync_ts = NULL;
> > +     tsync_context->sync_offsets = NULL;
> > +     tsync_context->sync_count = 0;
> > +     tsync_context->sync_size = 0;
> > +     pthread_mutex_destroy(&tsync->lock);
> > +     pthread_cond_destroy(&tsync->cond);
> > +     free(tsync->clock_str);
>
> I would think we would want a free(tsync) here. As the name of the
> function suggests.
>
There is no API to allocate it, that's why this function does not free
the memory. There is one use case where this memory is not allocated,
and free(tsync) will not work for it.

[ .. ]
> > +
> > +unsigned int tracecmd_guest_tsync(char *tsync_protos,
> > +                               unsigned int tsync_protos_size, char *clock,
> > +                               unsigned int *tsync_port, pthread_t *thr_id)
> > +{
> > +     struct tracecmd_time_sync *tsync = NULL;
> > +     cpu_set_t *pin_mask = NULL;
> > +     pthread_attr_t attrib;
> > +     size_t mask_size = 0;
> > +     unsigned int proto;
> > +     int ret;
> > +     int fd;
> > +
> > +     fd = -1;
> > +     proto = tracecmd_tsync_proto_select(tsync_protos, tsync_protos_size);
> > +     if (!proto)
> > +             return 0;
> > +#ifdef VSOCK
> > +     fd = trace_make_vsock(VMADDR_PORT_ANY);
> > +     if (fd < 0)
> > +             goto error;
> > +
> > +     ret = trace_get_vsock_port(fd, tsync_port);
> > +     if (ret < 0)
> > +             goto error;
> > +#else
> > +     return 0;
>
> If we have no synchronization support, shouldn't this return an error?

This function returns the id of negotiated time sync protocol. 0 means the
negotiation was not successful, no protocol is selected. When the caller
receives 0, it means we have no synchronization with the peer.

>
[ .. ]
>
> You don't need the if statement. free() can take a NULL pointer.
>
> Anyway, it's looking good. I like a lot of what you did. Especially
> with the helpers you created.
>
> I still need to take a deeper look at this and the following patches.
> I'm thinking that this patch could possibly be broken up into two or
> three patches. One patch to create the protocol, another one or two
> that use the protocol.
>
> Although we are very close to getting this in, I've been thinking more
> that we should release 2.9, without the time sync. We may need to just
> up the protocol when we implement the synchronization.
>
> I'll look more at this on Monday.
>
> Cheers!
>
> -- Steve
>
Thanks, Steven!
I'll  send the next  version, addressing your comments.
>
>
> > +             free(tsync);
> > +     }
> > +     if (fd > 0)
> > +             close(fd);
> > +     return 0;
> > +}
> > diff --git a/tracecmd/trace-usage.c b/tracecmd/trace-usage.c
> > index 05ec021..9fa61e1 100644
> > --- a/tracecmd/trace-usage.c
> > +++ b/tracecmd/trace-usage.c
> > @@ -60,6 +60,10 @@ static struct usage_help usage_help[] = {
> >               "          --no-filter include trace-cmd threads in the trace\n"
> >               "          --proc-map save the traced processes address map into the trace.dat file\n"
> >               "          --user execute the specified [command ...] as given user\n"
> > +             "          --tsync-interval set the loop interval, in ms, for timestamps synchronization with guests:"
> > +             "               If a negative number is specified, timestamps synchronization is disabled"
> > +             "               If 0 is specified, no loop is performed - timestamps offset is calculated only twice,"
> > +             "                                                         at the beginnig and at the end of the trace\n"
> >       },
> >       {
> >               "start",
>


-- 
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center

Re: [PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization

[Steven Rostedt]

On Fri, 31 Jan 2020 09:53:41 +0000
Tzvetomir Stoyanov <tstoyanov@vmware.com> wrote:

> On Sat, Dec 21, 2019 at 6:48 AM Steven Rostedt <rostedt@goodmis.org> wrote:
> >  
>  [ .. ]
> > > +#define PROTO_MASK_SIZE (sizeof(char))  
> >
> > I'm thinking that declaring a mask the size of 1 is a bit overkill.
> >  
> This define is a leftover from the previous implementation of this
> bitmask, where
> the size was 4 bytes. It was very easy to switch to 1 byte using the
> define, that's
> why I would prefer to keep it - in case we decide to change the size again.
> The code below is written with the assumption that the size could be
> more than 1 byte.

OK, that makes more sense.

> 
> [ .. ]
> > > + */
> > > +void tracecmd_tsync_free(struct tracecmd_time_sync *tsync)
> > > +{
> > > +     struct clock_sync_context *tsync_context;
> > > +     struct tsync_proto *proto;
> > > +
> > > +     if (!tsync->context)
> > > +             return;
> > > +     tsync_context = (struct clock_sync_context *)tsync->context;
> > > +
> > > +     proto = tsync_proto_find(tsync->sync_proto);
> > > +     if (proto && proto->clock_sync_free)
> > > +             proto->clock_sync_free(tsync);
> > > +
> > > +     clock_synch_delete_instance(tsync_context->vinst);
> > > +     tsync_context->vinst = NULL;
> > > +
> > > +     free(tsync_context->sync_ts);
> > > +     free(tsync_context->sync_offsets);
> > > +     tsync_context->sync_ts = NULL;
> > > +     tsync_context->sync_offsets = NULL;
> > > +     tsync_context->sync_count = 0;
> > > +     tsync_context->sync_size = 0;
> > > +     pthread_mutex_destroy(&tsync->lock);
> > > +     pthread_cond_destroy(&tsync->cond);
> > > +     free(tsync->clock_str);  
> >
> > I would think we would want a free(tsync) here. As the name of the
> > function suggests.
> >  
> There is no API to allocate it, that's why this function does not free
> the memory. There is one use case where this memory is not allocated,
> and free(tsync) will not work for it.

Then perhaps we should call it: tracecmd_tsync_cleanup(), as that's
what it is doing. _free() usually means you are actually freeing what
you pass in.


> 
> [ .. ]
> > > +
> > > +unsigned int tracecmd_guest_tsync(char *tsync_protos,
> > > +                               unsigned int tsync_protos_size, char *clock,
> > > +                               unsigned int *tsync_port, pthread_t *thr_id)
> > > +{
> > > +     struct tracecmd_time_sync *tsync = NULL;
> > > +     cpu_set_t *pin_mask = NULL;
> > > +     pthread_attr_t attrib;
> > > +     size_t mask_size = 0;
> > > +     unsigned int proto;
> > > +     int ret;
> > > +     int fd;
> > > +
> > > +     fd = -1;
> > > +     proto = tracecmd_tsync_proto_select(tsync_protos, tsync_protos_size);
> > > +     if (!proto)
> > > +             return 0;
> > > +#ifdef VSOCK
> > > +     fd = trace_make_vsock(VMADDR_PORT_ANY);
> > > +     if (fd < 0)
> > > +             goto error;
> > > +
> > > +     ret = trace_get_vsock_port(fd, tsync_port);
> > > +     if (ret < 0)
> > > +             goto error;
> > > +#else
> > > +     return 0;  
> >
> > If we have no synchronization support, shouldn't this return an error?  
> 
> This function returns the id of negotiated time sync protocol. 0 means the
> negotiation was not successful, no protocol is selected. When the caller
> receives 0, it means we have no synchronization with the peer.

OK, so this function definitely needs a "kernel doc" header explaining
this.

-- Steve