From d363c2a880c611eea3d754a618b6125bac7f3044 Mon Sep 17 00:00:00 2001 From: Fernand Sieber Date: Tue, 18 Jun 2024 11:03:39 +0200 Subject: [PATCH] perf: Timehist account sch delay for scheduled out running 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 Reviewed-by: Madadi Vineeth Reddy Signed-off-by: Namhyung Kim Link: https://lore.kernel.org/r/20240618090339.87482-1-sieberf@amazon.com --- tools/perf/Documentation/perf-sched.txt | 4 ++-- tools/perf/builtin-sched.c | 5 ++++- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt index a216d2991b19..74c812f7a4a4 100644 --- a/tools/perf/Documentation/perf-sched.txt +++ b/tools/perf/Documentation/perf-sched.txt @@ -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) diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index 8cdf18139a7e..aa59f763ca46 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -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);