Zimuzo reported seeing occasional cases in perfetto traces where
tasks went from sleeping directly to trace_sched_wakeup()
without always seeing a trace_sched_waking().
Looking at the code, trace_sched_wakeup() is only called in
ttwu_do_wakeup()
The call paths that get you to ttwu_do_wakeup() are:
try_to_wake_up() -> ttwu_do_wakeup()
try_to_wake_up() -> ttwu_runnable() -> ttwu_do_wakeup()
try_to_wake_up() -> ttwu_queue() -> ttwu_do_activate() -> ttwu_do_wakeup()
sched_ttwu_pending() -> ttwu_do_activate() -> ttwu_do_wakeup()
where trace_sched_waking() is currently called only in
try_to_wake_up().
So add a trace_sched_waking() call to sched_ttwu_pending(), so
we see the same state machine transitions.
With this change, the number of unexpected state transitions in
perfetto was greatly reduced.
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Vincent Guittot <[email protected]>
Cc: Dietmar Eggemann <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Ben Segall <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Daniel Bristot de Oliveira <[email protected]>
Cc: Phil Auld <[email protected]>
Cc: Valentin Schneider <[email protected]>
Cc: [email protected]
Reviewed-by: Phil Auld <[email protected]>
Reported-by: Zimuzo Ezeozue <[email protected]>
Signed-off-by: John Stultz <[email protected]>
---
v2:
* Minor commit message fix suggested by Phil Auld
---
kernel/sched/core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9116bcc90346..233f06360d6a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3894,6 +3894,7 @@ void sched_ttwu_pending(void *arg)
if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
set_task_cpu(p, cpu_of(rq));
+ trace_sched_waking(p);
ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
}
--
2.44.0.rc1.240.g4c46232300-goog