tools/perf/Documentation/perf-sched.txt | 8 ++ tools/perf/builtin-sched.c | 112 ++++++++++++++++-------- 2 files changed, 82 insertions(+), 38 deletions(-)
pre-migration wait time is the time that a task unnecessarily spends
on the runqueue of a CPU but doesn't get switched-in there. In terms
of tracepoints, it is the time between sched:sched_wakeup and
sched:sched_migrate_task.
Let's say a task woke up on CPU2, then it got migrated to CPU4 and
then it's switched-in to CPU4. So, here pre-migration wait time is
time that it was waiting on runqueue of CPU2 after it is woken up.
The general pattern for pre-migration to occur is:
sched:sched_wakeup
sched:sched_migrate_task
sched:sched_switch
So, this option expects sched_wakeup also to be recorded and fails
if attempted to use the option without sched:sched_wakeup tracepoint.
pre-migrations are generally not useful and it increases migrations.
This metric would be helpful in testing patches mainly related to wakeup
and load-balancer code paths as better wakeup logic would choose an
optimal CPU where task would be switched-in and thereby reducing pre-
migrations.
The sample output(s) when -P or --pre-migrations is used:
=================
time cpu task name wait time sch delay run time pre-mig time
[tid/pid] (msec) (msec) (msec) (msec)
--------------- ------ ------------------------------ --------- --------- --------- ---------
103032.721020 [0000] perf[47206] 0.000 0.000 0.000 0.000
103032.721034 [0000] migration/0[18] 0.000 0.003 0.013 0.000
103032.736716 [0001] schbench[47229/47207] 10.664 9.231 0.039 9.170
103032.736719 [0005] <idle> 0.000 0.000 15.405 0.000
103032.736726 [0003] schbench[47216/47207] 11.251 9.193 0.022 9.126
103032.736727 [0001] schbench[47228/47207] 10.752 9.264 0.010 9.169
103032.736731 [0007] <idle> 0.000 0.000 15.314 0.000
103032.736739 [0008] <idle> 0.000 0.000 15.249 0.000
103032.736742 [0003] schbench[47257/47207] 9.498 9.184 0.015 9.100
51370.894024 [0012] schbench[38775/38770] 21.047 21.047 8.950 0.000
51370.894024 [0008] schbench[38781/38770] 39.597 39.448 9.984 39.437
51370.894025 [0009] stress-ng-cpu[38743] 7.971 7.971 9.997 0.000
Changes since v1:
- Use timehist_sched_wakeup_event() to get the sched_wakeup time. (Namhyung Kim)
- Rebase against perf-tools-next commit b38c49d8296b ("perf/test: Speed up test
case perf annotate basic tests")
Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
---
tools/perf/Documentation/perf-sched.txt | 8 ++
tools/perf/builtin-sched.c | 112 ++++++++++++++++--------
2 files changed, 82 insertions(+), 38 deletions(-)
diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
index 3db64954a267..7935499b88b0 100644
--- a/tools/perf/Documentation/perf-sched.txt
+++ b/tools/perf/Documentation/perf-sched.txt
@@ -221,6 +221,14 @@ OPTIONS for 'perf sched timehist'
priorities are specified with -: 120-129. A combination of both can also be
provided: 0,120-129.
+-P::
+--pre-migrations::
+ Show pre-migration wait time. pre-migration wait time is the time spent
+ by a task waiting on a runqueue but not getting the chance to run there
+ and is migrated to a different runqueue where it is finally run. This
+ time between migrate_task and sched_wakeup is the pre-migration wait
+ time. This option is valid only if sched_wakeup tracepoint is recorded.
+
OPTIONS for 'perf sched replay'
------------------------------
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index fdf979aaf275..02fe0ec41141 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -225,6 +225,7 @@ struct perf_sched {
bool show_wakeups;
bool show_next;
bool show_migrations;
+ bool pre_migrations;
bool show_state;
bool show_prio;
u64 skipped_samples;
@@ -244,7 +245,10 @@ struct thread_runtime {
u64 dt_iowait; /* time between CPU access by iowait (off cpu) */
u64 dt_preempt; /* time between CPU access by preempt (off cpu) */
u64 dt_delay; /* time between wakeup and sched-in */
+ u64 dt_pre_mig; /* time between migration and wakeup */
u64 ready_to_run; /* time of wakeup */
+ u64 woken; /* time when sched_wakeup tracepoint is hit */
+ u64 migrated; /* time when a thread is migrated */
struct stats run_stats;
u64 total_run_time;
@@ -252,6 +256,7 @@ struct thread_runtime {
u64 total_iowait_time;
u64 total_preempt_time;
u64 total_delay_time;
+ u64 total_pre_mig_time;
char last_state;
@@ -2073,14 +2078,15 @@ static void timehist_header(struct perf_sched *sched)
printf(" ");
}
- if (sched->show_prio) {
- printf(" %-*s %-*s %9s %9s %9s",
- comm_width, "task name", MAX_PRIO_STR_LEN, "prio",
- "wait time", "sch delay", "run time");
- } else {
- printf(" %-*s %9s %9s %9s", comm_width,
- "task name", "wait time", "sch delay", "run time");
- }
+ printf(" %-*s", comm_width, "task name");
+
+ if (sched->show_prio)
+ printf(" %-*s", MAX_PRIO_STR_LEN, "prio");
+
+ printf(" %9s %9s %9s", "wait time", "sch delay", "run time");
+
+ if (sched->pre_migrations)
+ printf(" %9s", "pre-mig time");
if (sched->show_state)
printf(" %s", "state");
@@ -2095,17 +2101,15 @@ static void timehist_header(struct perf_sched *sched)
if (sched->show_cpu_visual)
printf(" %*s ", ncpus, "");
- if (sched->show_prio) {
- printf(" %-*s %-*s %9s %9s %9s",
- comm_width, "[tid/pid]", MAX_PRIO_STR_LEN, "",
- "(msec)", "(msec)", "(msec)");
- } else {
- printf(" %-*s %9s %9s %9s", comm_width,
- "[tid/pid]", "(msec)", "(msec)", "(msec)");
- }
+ printf(" %-*s", comm_width, "[tid/pid]");
- if (sched->show_state)
- printf(" %5s", "");
+ if (sched->show_prio)
+ printf(" %-*s", MAX_PRIO_STR_LEN, "");
+
+ printf(" %9s %9s %9s", "(msec)", "(msec)", "(msec)");
+
+ if (sched->pre_migrations)
+ printf(" %9s", "(msec)");
printf("\n");
@@ -2117,15 +2121,15 @@ static void timehist_header(struct perf_sched *sched)
if (sched->show_cpu_visual)
printf(" %.*s ", ncpus, graph_dotted_line);
- if (sched->show_prio) {
- printf(" %.*s %.*s %.9s %.9s %.9s",
- comm_width, graph_dotted_line, MAX_PRIO_STR_LEN, graph_dotted_line,
- graph_dotted_line, graph_dotted_line, graph_dotted_line);
- } else {
- printf(" %.*s %.9s %.9s %.9s", comm_width,
- graph_dotted_line, graph_dotted_line, graph_dotted_line,
- graph_dotted_line);
- }
+ printf(" %.*s", comm_width, graph_dotted_line);
+
+ if (sched->show_prio)
+ printf(" %.*s", MAX_PRIO_STR_LEN, graph_dotted_line);
+
+ printf(" %.9s %.9s %.9s", graph_dotted_line, graph_dotted_line, graph_dotted_line);
+
+ if (sched->pre_migrations)
+ printf(" %.9s", graph_dotted_line);
if (sched->show_state)
printf(" %.5s", graph_dotted_line);
@@ -2180,6 +2184,8 @@ static void timehist_print_sample(struct perf_sched *sched,
print_sched_time(tr->dt_delay, 6);
print_sched_time(tr->dt_run, 6);
+ if (sched->pre_migrations)
+ print_sched_time(tr->dt_pre_mig, 6);
if (sched->show_state)
printf(" %5c ", thread__tid(thread) == 0 ? 'I' : state);
@@ -2239,6 +2245,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
r->dt_iowait = 0;
r->dt_preempt = 0;
r->dt_run = 0;
+ r->dt_pre_mig = 0;
if (tprev) {
r->dt_run = t - tprev;
@@ -2247,6 +2254,11 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
pr_debug("time travel: wakeup time for task > previous sched_switch event\n");
else
r->dt_delay = tprev - r->ready_to_run;
+
+ if (r->woken && r->migrated) {
+ if ((r->migrated > r->woken) && (r->migrated < tprev))
+ r->dt_pre_mig = r->migrated - r->woken;
+ }
}
if (r->last_time > tprev)
@@ -2270,6 +2282,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
r->total_sleep_time += r->dt_sleep;
r->total_iowait_time += r->dt_iowait;
r->total_preempt_time += r->dt_preempt;
+ r->total_pre_mig_time += r->dt_pre_mig;
}
static bool is_idle_sample(struct perf_sample *sample,
@@ -2598,13 +2611,19 @@ static int timehist_sched_wakeup_event(const struct perf_tool *tool,
if (tr == NULL)
return -1;
- if (tr->ready_to_run == 0)
- tr->ready_to_run = sample->time;
+ if (!strcmp(evsel__name(evsel), "sched:sched_waking")) {
+ if (tr->ready_to_run == 0)
+ tr->ready_to_run = sample->time;
- /* show wakeups if requested */
- if (sched->show_wakeups &&
- !perf_time__skip_sample(&sched->ptime, sample->time))
- timehist_print_wakeup_event(sched, evsel, sample, machine, thread);
+ /* show wakeups if requested */
+ if (sched->show_wakeups &&
+ !perf_time__skip_sample(&sched->ptime, sample->time))
+ timehist_print_wakeup_event(sched, evsel, sample, machine, thread);
+ } else {
+ /* keep track of wakeup time for pre-migration */
+ if (tr->woken == 0)
+ tr->woken = sample->time;
+ }
return 0;
}
@@ -2684,8 +2703,14 @@ static int timehist_migrate_task_event(const struct perf_tool *tool,
tr->migrations++;
+ if (tr->migrated == 0)
+ tr->migrated = sample->time;
+
/* show migrations if requested */
- timehist_print_migration_event(sched, evsel, sample, machine, thread);
+ if (sched->show_migrations) {
+ timehist_print_migration_event(sched, evsel, sample,
+ machine, thread);
+ }
return 0;
}
@@ -2836,11 +2861,14 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
/* last state is used to determine where to account wait time */
tr->last_state = state;
- /* sched out event for task so reset ready to run time */
+ /* sched out event for task so reset ready to run time, woken and migrated time */
if (state == 'R')
tr->ready_to_run = t;
else
tr->ready_to_run = 0;
+
+ tr->woken = 0;
+ tr->migrated = 0;
}
evsel__save_time(evsel, sample->time, sample->cpu);
@@ -3267,7 +3295,8 @@ static int perf_sched__timehist(struct perf_sched *sched)
setup_pager();
/* prefer sched_waking if it is captured */
- if (evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
+ if (!sched->pre_migrations &&
+ evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
handlers[1].handler = timehist_sched_wakeup_ignore;
/* setup per-evsel handlers */
@@ -3280,8 +3309,14 @@ static int perf_sched__timehist(struct perf_sched *sched)
goto out;
}
- if (sched->show_migrations &&
- perf_session__set_tracepoints_handlers(session, migrate_handlers))
+ if (sched->pre_migrations && !evlist__find_tracepoint_by_name(session->evlist,
+ "sched:sched_wakeup")) {
+ pr_err("No sched_wakeup events found. sched_wakeup tracepoint is mandatory for -P option\n");
+ goto out;
+ }
+
+ if ((sched->show_migrations || sched->pre_migrations) &&
+ perf_session__set_tracepoints_handlers(session, migrate_handlers))
goto out;
/* pre-allocate struct for per-CPU idle stats */
@@ -3823,6 +3858,7 @@ int cmd_sched(int argc, const char **argv)
OPT_BOOLEAN(0, "show-prio", &sched.show_prio, "Show task priority"),
OPT_STRING(0, "prio", &sched.prio_str, "prio",
"analyze events only for given task priority(ies)"),
+ OPT_BOOLEAN('P', "pre-migrations", &sched.pre_migrations, "Show pre-migration wait time"),
OPT_PARENT(sched_options)
};
--
2.43.2On Tue, Oct 01, 2024 at 04:36:20PM +0530, Madadi Vineeth Reddy wrote:
> pre-migration wait time is the time that a task unnecessarily spends
> on the runqueue of a CPU but doesn't get switched-in there. In terms
> of tracepoints, it is the time between sched:sched_wakeup and
> sched:sched_migrate_task.
>
> Let's say a task woke up on CPU2, then it got migrated to CPU4 and
> then it's switched-in to CPU4. So, here pre-migration wait time is
> time that it was waiting on runqueue of CPU2 after it is woken up.
>
> The general pattern for pre-migration to occur is:
> sched:sched_wakeup
> sched:sched_migrate_task
> sched:sched_switch
> So, this option expects sched_wakeup also to be recorded and fails
> if attempted to use the option without sched:sched_wakeup tracepoint.
>
> pre-migrations are generally not useful and it increases migrations.
> This metric would be helpful in testing patches mainly related to wakeup
> and load-balancer code paths as better wakeup logic would choose an
> optimal CPU where task would be switched-in and thereby reducing pre-
> migrations.
>
> The sample output(s) when -P or --pre-migrations is used:
> =================
> time cpu task name wait time sch delay run time pre-mig time
> [tid/pid] (msec) (msec) (msec) (msec)
> --------------- ------ ------------------------------ --------- --------- --------- ---------
> 103032.721020 [0000] perf[47206] 0.000 0.000 0.000 0.000
> 103032.721034 [0000] migration/0[18] 0.000 0.003 0.013 0.000
> 103032.736716 [0001] schbench[47229/47207] 10.664 9.231 0.039 9.170
> 103032.736719 [0005] <idle> 0.000 0.000 15.405 0.000
> 103032.736726 [0003] schbench[47216/47207] 11.251 9.193 0.022 9.126
> 103032.736727 [0001] schbench[47228/47207] 10.752 9.264 0.010 9.169
> 103032.736731 [0007] <idle> 0.000 0.000 15.314 0.000
> 103032.736739 [0008] <idle> 0.000 0.000 15.249 0.000
> 103032.736742 [0003] schbench[47257/47207] 9.498 9.184 0.015 9.100
>
> 51370.894024 [0012] schbench[38775/38770] 21.047 21.047 8.950 0.000
> 51370.894024 [0008] schbench[38781/38770] 39.597 39.448 9.984 39.437
> 51370.894025 [0009] stress-ng-cpu[38743] 7.971 7.971 9.997 0.000
>
> Changes since v1:
> - Use timehist_sched_wakeup_event() to get the sched_wakeup time. (Namhyung Kim)
> - Rebase against perf-tools-next commit b38c49d8296b ("perf/test: Speed up test
> case perf annotate basic tests")
>
> Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
> ---
> tools/perf/Documentation/perf-sched.txt | 8 ++
> tools/perf/builtin-sched.c | 112 ++++++++++++++++--------
> 2 files changed, 82 insertions(+), 38 deletions(-)
>
> diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
> index 3db64954a267..7935499b88b0 100644
> --- a/tools/perf/Documentation/perf-sched.txt
> +++ b/tools/perf/Documentation/perf-sched.txt
> @@ -221,6 +221,14 @@ OPTIONS for 'perf sched timehist'
> priorities are specified with -: 120-129. A combination of both can also be
> provided: 0,120-129.
>
> +-P::
> +--pre-migrations::
> + Show pre-migration wait time. pre-migration wait time is the time spent
> + by a task waiting on a runqueue but not getting the chance to run there
> + and is migrated to a different runqueue where it is finally run. This
> + time between migrate_task and sched_wakeup is the pre-migration wait
> + time. This option is valid only if sched_wakeup tracepoint is recorded.
> +
> OPTIONS for 'perf sched replay'
> ------------------------------
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index fdf979aaf275..02fe0ec41141 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -225,6 +225,7 @@ struct perf_sched {
> bool show_wakeups;
> bool show_next;
> bool show_migrations;
> + bool pre_migrations;
> bool show_state;
> bool show_prio;
> u64 skipped_samples;
> @@ -244,7 +245,10 @@ struct thread_runtime {
> u64 dt_iowait; /* time between CPU access by iowait (off cpu) */
> u64 dt_preempt; /* time between CPU access by preempt (off cpu) */
> u64 dt_delay; /* time between wakeup and sched-in */
> + u64 dt_pre_mig; /* time between migration and wakeup */
> u64 ready_to_run; /* time of wakeup */
> + u64 woken; /* time when sched_wakeup tracepoint is hit */
> + u64 migrated; /* time when a thread is migrated */
>
> struct stats run_stats;
> u64 total_run_time;
> @@ -252,6 +256,7 @@ struct thread_runtime {
> u64 total_iowait_time;
> u64 total_preempt_time;
> u64 total_delay_time;
> + u64 total_pre_mig_time;
>
> char last_state;
>
> @@ -2073,14 +2078,15 @@ static void timehist_header(struct perf_sched *sched)
> printf(" ");
> }
>
> - if (sched->show_prio) {
> - printf(" %-*s %-*s %9s %9s %9s",
> - comm_width, "task name", MAX_PRIO_STR_LEN, "prio",
> - "wait time", "sch delay", "run time");
> - } else {
> - printf(" %-*s %9s %9s %9s", comm_width,
> - "task name", "wait time", "sch delay", "run time");
> - }
> + printf(" %-*s", comm_width, "task name");
> +
> + if (sched->show_prio)
> + printf(" %-*s", MAX_PRIO_STR_LEN, "prio");
> +
> + printf(" %9s %9s %9s", "wait time", "sch delay", "run time");
> +
> + if (sched->pre_migrations)
> + printf(" %9s", "pre-mig time");
>
> if (sched->show_state)
> printf(" %s", "state");
> @@ -2095,17 +2101,15 @@ static void timehist_header(struct perf_sched *sched)
> if (sched->show_cpu_visual)
> printf(" %*s ", ncpus, "");
>
> - if (sched->show_prio) {
> - printf(" %-*s %-*s %9s %9s %9s",
> - comm_width, "[tid/pid]", MAX_PRIO_STR_LEN, "",
> - "(msec)", "(msec)", "(msec)");
> - } else {
> - printf(" %-*s %9s %9s %9s", comm_width,
> - "[tid/pid]", "(msec)", "(msec)", "(msec)");
> - }
> + printf(" %-*s", comm_width, "[tid/pid]");
>
> - if (sched->show_state)
> - printf(" %5s", "");
> + if (sched->show_prio)
> + printf(" %-*s", MAX_PRIO_STR_LEN, "");
> +
> + printf(" %9s %9s %9s", "(msec)", "(msec)", "(msec)");
> +
> + if (sched->pre_migrations)
> + printf(" %9s", "(msec)");
>
> printf("\n");
>
> @@ -2117,15 +2121,15 @@ static void timehist_header(struct perf_sched *sched)
> if (sched->show_cpu_visual)
> printf(" %.*s ", ncpus, graph_dotted_line);
>
> - if (sched->show_prio) {
> - printf(" %.*s %.*s %.9s %.9s %.9s",
> - comm_width, graph_dotted_line, MAX_PRIO_STR_LEN, graph_dotted_line,
> - graph_dotted_line, graph_dotted_line, graph_dotted_line);
> - } else {
> - printf(" %.*s %.9s %.9s %.9s", comm_width,
> - graph_dotted_line, graph_dotted_line, graph_dotted_line,
> - graph_dotted_line);
> - }
> + printf(" %.*s", comm_width, graph_dotted_line);
> +
> + if (sched->show_prio)
> + printf(" %.*s", MAX_PRIO_STR_LEN, graph_dotted_line);
> +
> + printf(" %.9s %.9s %.9s", graph_dotted_line, graph_dotted_line, graph_dotted_line);
> +
> + if (sched->pre_migrations)
> + printf(" %.9s", graph_dotted_line);
>
> if (sched->show_state)
> printf(" %.5s", graph_dotted_line);
> @@ -2180,6 +2184,8 @@ static void timehist_print_sample(struct perf_sched *sched,
>
> print_sched_time(tr->dt_delay, 6);
> print_sched_time(tr->dt_run, 6);
> + if (sched->pre_migrations)
> + print_sched_time(tr->dt_pre_mig, 6);
>
> if (sched->show_state)
> printf(" %5c ", thread__tid(thread) == 0 ? 'I' : state);
> @@ -2239,6 +2245,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
> r->dt_iowait = 0;
> r->dt_preempt = 0;
> r->dt_run = 0;
> + r->dt_pre_mig = 0;
>
> if (tprev) {
> r->dt_run = t - tprev;
> @@ -2247,6 +2254,11 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
> pr_debug("time travel: wakeup time for task > previous sched_switch event\n");
> else
> r->dt_delay = tprev - r->ready_to_run;
> +
> + if (r->woken && r->migrated) {
> + if ((r->migrated > r->woken) && (r->migrated < tprev))
> + r->dt_pre_mig = r->migrated - r->woken;
> + }
> }
>
> if (r->last_time > tprev)
> @@ -2270,6 +2282,7 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
> r->total_sleep_time += r->dt_sleep;
> r->total_iowait_time += r->dt_iowait;
> r->total_preempt_time += r->dt_preempt;
> + r->total_pre_mig_time += r->dt_pre_mig;
> }
>
> static bool is_idle_sample(struct perf_sample *sample,
> @@ -2598,13 +2611,19 @@ static int timehist_sched_wakeup_event(const struct perf_tool *tool,
> if (tr == NULL)
> return -1;
>
> - if (tr->ready_to_run == 0)
> - tr->ready_to_run = sample->time;
> + if (!strcmp(evsel__name(evsel), "sched:sched_waking")) {
I guess it won't work when there's no sched_waking event. Can you
simply handle pre-migration in sched_waking?
Thanks,
Namhyung
> + if (tr->ready_to_run == 0)
> + tr->ready_to_run = sample->time;
>
> - /* show wakeups if requested */
> - if (sched->show_wakeups &&
> - !perf_time__skip_sample(&sched->ptime, sample->time))
> - timehist_print_wakeup_event(sched, evsel, sample, machine, thread);
> + /* show wakeups if requested */
> + if (sched->show_wakeups &&
> + !perf_time__skip_sample(&sched->ptime, sample->time))
> + timehist_print_wakeup_event(sched, evsel, sample, machine, thread);
> + } else {
> + /* keep track of wakeup time for pre-migration */
> + if (tr->woken == 0)
> + tr->woken = sample->time;
> + }
>
> return 0;
> }
> @@ -2684,8 +2703,14 @@ static int timehist_migrate_task_event(const struct perf_tool *tool,
>
> tr->migrations++;
>
> + if (tr->migrated == 0)
> + tr->migrated = sample->time;
> +
> /* show migrations if requested */
> - timehist_print_migration_event(sched, evsel, sample, machine, thread);
> + if (sched->show_migrations) {
> + timehist_print_migration_event(sched, evsel, sample,
> + machine, thread);
> + }
>
> return 0;
> }
> @@ -2836,11 +2861,14 @@ static int timehist_sched_change_event(const struct perf_tool *tool,
> /* last state is used to determine where to account wait time */
> tr->last_state = state;
>
> - /* sched out event for task so reset ready to run time */
> + /* sched out event for task so reset ready to run time, woken and migrated time */
> if (state == 'R')
> tr->ready_to_run = t;
> else
> tr->ready_to_run = 0;
> +
> + tr->woken = 0;
> + tr->migrated = 0;
> }
>
> evsel__save_time(evsel, sample->time, sample->cpu);
> @@ -3267,7 +3295,8 @@ static int perf_sched__timehist(struct perf_sched *sched)
> setup_pager();
>
> /* prefer sched_waking if it is captured */
> - if (evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
> + if (!sched->pre_migrations &&
> + evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
> handlers[1].handler = timehist_sched_wakeup_ignore;
>
> /* setup per-evsel handlers */
> @@ -3280,8 +3309,14 @@ static int perf_sched__timehist(struct perf_sched *sched)
> goto out;
> }
>
> - if (sched->show_migrations &&
> - perf_session__set_tracepoints_handlers(session, migrate_handlers))
> + if (sched->pre_migrations && !evlist__find_tracepoint_by_name(session->evlist,
> + "sched:sched_wakeup")) {
> + pr_err("No sched_wakeup events found. sched_wakeup tracepoint is mandatory for -P option\n");
> + goto out;
> + }
> +
> + if ((sched->show_migrations || sched->pre_migrations) &&
> + perf_session__set_tracepoints_handlers(session, migrate_handlers))
> goto out;
>
> /* pre-allocate struct for per-CPU idle stats */
> @@ -3823,6 +3858,7 @@ int cmd_sched(int argc, const char **argv)
> OPT_BOOLEAN(0, "show-prio", &sched.show_prio, "Show task priority"),
> OPT_STRING(0, "prio", &sched.prio_str, "prio",
> "analyze events only for given task priority(ies)"),
> + OPT_BOOLEAN('P', "pre-migrations", &sched.pre_migrations, "Show pre-migration wait time"),
> OPT_PARENT(sched_options)
> };
>
> --
> 2.43.2
>
Hi Namhyung,
On 02/10/24 06:12, Namhyung Kim wrote:
> On Tue, Oct 01, 2024 at 04:36:20PM +0530, Madadi Vineeth Reddy wrote:
>> pre-migration wait time is the time that a task unnecessarily spends
>> on the runqueue of a CPU but doesn't get switched-in there. In terms
>> of tracepoints, it is the time between sched:sched_wakeup and
>> sched:sched_migrate_task.
[snip]
>> static bool is_idle_sample(struct perf_sample *sample,
>> @@ -2598,13 +2611,19 @@ static int timehist_sched_wakeup_event(const struct perf_tool *tool,
>> if (tr == NULL)
>> return -1;
>>
>> - if (tr->ready_to_run == 0)
>> - tr->ready_to_run = sample->time;
>> + if (!strcmp(evsel__name(evsel), "sched:sched_waking")) {
>
> I guess it won't work when there's no sched_waking event. Can you
> simply handle pre-migration in sched_waking?
>
I believe it should still work even without the sched_waking event because
I've updated the condition to ensure that timehist_sched_wakeup_ignore is
not selected when the pre-migration option is enabled.
> Thanks,
> Namhyung
>
>
>> + if (tr->ready_to_run == 0)
>> + tr->ready_to_run = sample->time;
[snip]
>> /* prefer sched_waking if it is captured */
>> - if (evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
>> + if (!sched->pre_migrations &&
>> + evlist__find_tracepoint_by_name(session->evlist, "sched:sched_waking"))
>> handlers[1].handler = timehist_sched_wakeup_ignore;
In this case, it checks if pre-migration is enabled. If so, the handler will still
use timehist_sched_wakeup_event for the sched:sched_wakeup event.
The reason I initially chose the sched:sched_wakeup tracepoint instead of
sched:sched_waking is that there could be instances where the CPU chosen
during sched_waking may not match the actual CPU where the task ends up running,
as shown in the example below:
wdavdaemon 14789 [006] 31357.614692: sched:sched_waking: comm=wdavdaemon pid=14778 prio=120 target_cpu=005
[snip]
swapper 0 [002] 31357.614695: sched:sched_wakeup: wdavdaemon:14778 [120] CPU:002
However, since we are already accounting for the sched_migrate_task event occurring
between sched_waking and sched_switch and don't need to check target_cpu, switching
to sched_waking should work just as well, with only a very minor time difference.
I'll go ahead and send a v3 with sched_waking. Thanks again for the feedback.
Thanks,
Madadi Vineeth Reddy
>>
>> /* setup per-evsel handlers */
>> @@ -3280,8 +3309,14 @@ static int perf_sched__timehist(struct perf_sched *sched)
>> goto out;
>> }
>>
>> - if (sched->show_migrations &&
>> - perf_session__set_tracepoints_handlers(session, migrate_handlers))
>> + if (sched->pre_migrations && !evlist__find_tracepoint_by_name(session->evlist,
>> + "sched:sched_wakeup")) {
>> + pr_err("No sched_wakeup events found. sched_wakeup tracepoint is mandatory for -P option\n");
>> + goto out;
>> + }
>> +
>> + if ((sched->show_migrations || sched->pre_migrations) &&
>> + perf_session__set_tracepoints_handlers(session, migrate_handlers))
>> goto out;
>>
>> /* pre-allocate struct for per-CPU idle stats */
>> @@ -3823,6 +3858,7 @@ int cmd_sched(int argc, const char **argv)
>> OPT_BOOLEAN(0, "show-prio", &sched.show_prio, "Show task priority"),
>> OPT_STRING(0, "prio", &sched.prio_str, "prio",
>> "analyze events only for given task priority(ies)"),
>> + OPT_BOOLEAN('P', "pre-migrations", &sched.pre_migrations, "Show pre-migration wait time"),
>> OPT_PARENT(sched_options)
>> };
>>
>> --
>> 2.43.2
>>
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