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perf: Timehist account sch delay for scheduled out running

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When using perf timehist, sch delay is only computed for a waking task,
not for a pre empted task. This patches changes sch delay to account for
both. This makes sense as testing scheduling policy need to consider the
effect of scheduling delay globally, not only for waking tasks.

Example of `perf timehist` report before the patch for `stress` task
competing with each other.

First column is wait time, second column sch delay, third column
runtime.

1.492060 [0000]  s    stress[81]                          1.999      0.000      2.000      R  next: stress[83]
1.494060 [0000]  s    stress[83]                          2.000      0.000      2.000      R  next: stress[81]
1.496060 [0000]  s    stress[81]                          2.000      0.000      2.000      R  next: stress[83]
1.498060 [0000]  s    stress[83]                          2.000      0.000      1.999      R  next: stress[81]

After the patch, it looks like this (note that all wait time is not zero
anymore):

1.492060 [0000]  s    stress[81]                          1.999      1.999      2.000      R  next: stress[83]
1.494060 [0000]  s    stress[83]                          2.000      2.000      2.000      R  next: stress[81]
1.496060 [0000]  s    stress[81]                          2.000      2.000      2.000      R  next: stress[83]
1.498060 [0000]  s    stress[83]                          2.000      2.000      1.999      R  next: stress[81]

Signed-off-by: Fernand Sieber <sieberf@amazon.com>
Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240618090339.87482-1-sieberf@amazon.com
This commit is contained in:
Fernand Sieber 2024-06-18 11:03:39 +02:00 committed by Namhyung Kim
parent fcd094e52b
commit d363c2a880
2 changed files with 6 additions and 3 deletions
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4
tools/perf/Documentation/perf-sched.txt
View File

@ -64,8 +64,8 @@ There are several variants of 'perf sched':
By default it shows the individual schedule events, including the wait
time (time between sched-out and next sched-in events for the task), the
task scheduling delay (time between wakeup and actually running) and run
time for the task:
task scheduling delay (time between runnable and actually running) and
run time for the task:
time cpu task name wait time sch delay run time
[tid/pid] (msec) (msec) (msec)

5
tools/perf/builtin-sched.c
View File

@ -2659,7 +2659,10 @@ out:
tr->last_state = state;
/* sched out event for task so reset ready to run time */
tr->ready_to_run = 0;
if (state == 'R')
tr->ready_to_run = t;
else
tr->ready_to_run = 0;
}
evsel__save_time(evsel, sample->time, sample->cpu);