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From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v18 06/18] trace-cmd: Add new library API for reading ftrace buffers
Date: Fri, 13 Dec 2019 17:30:17 +0200
Message-ID: <20191213153029.133570-7-tz.stoyanov@gmail.com> (raw)
In-Reply-To: <20191213153029.133570-1-tz.stoyanov@gmail.com>

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


  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-13 15:30 [PATCH v18 00/18]Timestamp synchronization of host - guest tracing session Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 01/18] trace-cmd: Implement new lib API: tracecmd_local_events_system() Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 02/18] trace-cmd: Add support for negative time offsets in trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 03/18] trace-cmd: Add implementations of htonll() and ntohll() Tzvetomir Stoyanov (VMware)
2019-12-21  2:34   ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 04/18] trace-cmd: Add new library APIs for ftrace instances Tzvetomir Stoyanov (VMware)
2019-12-21  3:03   ` Steven Rostedt
2020-01-06 14:47     ` Tzvetomir Stoyanov
2019-12-13 15:30 ` [PATCH v18 05/18] trace-cmd: Add new library API for local CPU count Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` Tzvetomir Stoyanov (VMware) [this message]
2019-12-13 15:30 ` [PATCH v18 07/18] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 08/18] trace-cmd: Implement new API tracecmd_add_option_v() Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 09/18] trace-cmd: Add new API to generate a unique ID of the tracing session Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 10/18] trace-cmd: Store the session tracing ID in the trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-20 20:04   ` Steven Rostedt
2020-01-06 14:33     ` Tzvetomir Stoyanov
2019-12-13 15:30 ` [PATCH v18 11/18] trace-cmd: Exchange tracing IDs between host and guest Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 12/18] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT Tzvetomir Stoyanov (VMware)
2019-12-21  3:19   ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 13/18] trace-cmd: Add guest information in host's trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-20 20:52   ` Steven Rostedt
2020-01-06 14:43     ` Tzvetomir Stoyanov
2020-01-06 14:55       ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 14/18] trace-cmd: Add host trace clock as guest trace argument Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 15/18] trace-cmd: Refactor few trace-cmd internal functions Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization Tzvetomir Stoyanov (VMware)
2019-12-21  4:48   ` Steven Rostedt
2020-01-31  9:53     ` Tzvetomir Stoyanov
2020-01-31 14:49       ` Steven Rostedt
2019-12-13 15:30 ` [PATCH v18 17/18] trace-cmd: [POC] PTP-like algorithm " Tzvetomir Stoyanov (VMware)
2019-12-13 15:30 ` [PATCH v18 18/18] trace-cmd: Debug scripts for " Tzvetomir Stoyanov (VMware)

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