From: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
To: rostedt@goodmis.org
Cc: linux-trace-devel@vger.kernel.org
Subject: [PATCH v21 01/13] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM
Date: Mon, 2 Mar 2020 12:13:52 +0200 [thread overview]
Message-ID: <20200302101404.150035-2-tz.stoyanov@gmail.com> (raw)
In-Reply-To: <20200302101404.150035-1-tz.stoyanov@gmail.com>
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 | 84 ++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+)
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
index 29f27793..a5cf0640 100644
--- a/tracecmd/include/trace-local.h
+++ b/tracecmd/include/trace-local.h
@@ -247,6 +247,8 @@ 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 0a3851ad..3cbc832c 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3035,11 +3035,32 @@ struct guest {
char *name;
int cid;
int pid;
+ int cpu_max;
+ int *cpu_pid;
};
static struct guest *guests;
static size_t guests_len;
+static int set_vcpu_pid_mapping(struct guest *guest, int cpu, int pid)
+{
+ int *cpu_pid;
+ int i;
+
+ if (cpu >= guest->cpu_max) {
+ cpu_pid = realloc(guest->cpu_pid, (cpu + 1) * sizeof(int));
+ if (!cpu_pid)
+ return -1;
+ /* Handle sparse CPU numbers */
+ for (i = guest->cpu_max; i < cpu; i++)
+ guest->cpu_pid[i] = -1;
+ guest->cpu_max = cpu + 1;
+ guest->cpu_pid = cpu_pid;
+ }
+ guest->cpu_pid[cpu] = pid;
+ return 0;
+}
+
static char *get_qemu_guest_name(char *arg)
{
char *tok, *end = arg;
@@ -3052,6 +3073,49 @@ static char *get_qemu_guest_name(char *arg)
return arg;
}
+static int read_qemu_guests_pids(char *guest_task, struct guest *guest)
+{
+ struct dirent *entry;
+ char path[PATH_MAX];
+ char *buf = NULL;
+ size_t n = 0;
+ long vcpu;
+ long pid;
+ DIR *dir;
+ FILE *f;
+
+ snprintf(path, sizeof(path), "/proc/%s/task", guest_task);
+ dir = opendir(path);
+ if (!dir)
+ return -1;
+
+ 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 = strtol(buf + 4, NULL, 10);
+ pid = strtol(entry->d_name, NULL, 10);
+ if (vcpu < INT_MAX && pid < INT_MAX &&
+ vcpu >= 0 && pid >= 0) {
+ if (set_vcpu_pid_mapping(guest, vcpu, pid))
+ return -1;
+ }
+ }
+
+ fclose(f);
+ }
+ free(buf);
+ return 0;
+}
+
static void read_qemu_guests(void)
{
static bool initialized;
@@ -3115,6 +3179,10 @@ static void read_qemu_guests(void)
if (!is_qemu)
goto next;
+ if (read_qemu_guests_pids(entry->d_name, &guest))
+ warning("Failed to retrieve VPCU - PID mapping for guest %s",
+ guest.name ? guest.name : "Unknown");
+
guests = realloc(guests, (guests_len + 1) * sizeof(*guests));
if (!guests)
die("Can not allocate guest buffer");
@@ -3160,6 +3228,22 @@ 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)
+ return -1;
+
+ for (i = 0; i < guests_len; i++) {
+ if (guests[i].cpu_pid < 0 || guest_vcpu >= guests[i].cpu_max)
+ continue;
+ 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;
--
2.24.1
next prev parent reply other threads:[~2020-03-02 10:14 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-02 10:13 [PATCH v21 00/13] Timestamp synchronization of host - guest tracing session Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` Tzvetomir Stoyanov (VMware) [this message]
2020-03-02 16:25 ` [PATCH v21 01/13] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Steven Rostedt
2020-03-02 16:33 ` Steven Rostedt
2020-03-02 10:13 ` [PATCH v21 02/13] trace-cmd: Implement new API tracecmd_add_option_v() Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 03/13] trace-cmd: Add new API to generate a unique ID of the tracing session Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 04/13] trace-cmd: Store the session tracing ID in the trace.dat file Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 05/13] trace-cmd: Add definitions of htonll() and ntohll() Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 06/13] trace-cmd: Exchange tracing IDs between host and guest Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 07/13] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT Tzvetomir Stoyanov (VMware)
2020-03-02 10:13 ` [PATCH v21 08/13] trace-cmd: Add guest information in host's trace.dat file Tzvetomir Stoyanov (VMware)
2020-03-02 10:14 ` [PATCH v21 09/13] trace-cmd: Add host trace clock as guest trace argument Tzvetomir Stoyanov (VMware)
2020-03-02 10:14 ` [PATCH v21 10/13] trace-cmd: Refactor few trace-cmd internal functions Tzvetomir Stoyanov (VMware)
2020-03-02 10:14 ` [PATCH v21 11/13] trace-cmd: Basic infrastructure for host - guest timestamp synchronization Tzvetomir Stoyanov (VMware)
2020-03-02 16:43 ` Steven Rostedt
2020-03-04 9:11 ` Tzvetomir Stoyanov
2020-03-02 10:14 ` [PATCH v21 12/13] trace-cmd: [POC] PTP-like algorithm " Tzvetomir Stoyanov (VMware)
2020-03-02 10:14 ` [PATCH v21 13/13] trace-cmd: Debug scripts for " Tzvetomir Stoyanov (VMware)
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