Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [RFC PATCH 1/2] sched/tracing: Don't re-read p->state when emitting sched_switch event | Date | Thu, 09 Dec 2021 13:02:53 +0000 |
| |
On 08/12/21 15:12, Steven Rostedt wrote: > On Mon, 29 Nov 2021 12:36:00 +0000 > Valentin Schneider <valentin.schneider@arm.com> wrote: > >> As of commit >> >> c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") >> >> the following sequence becomes possible: >> >> p->__state = TASK_INTERRUPTIBLE; >> __schedule() >> deactivate_task(p); >> ttwu() >> READ !p->on_rq >> p->__state=TASK_WAKING >> trace_sched_switch() >> __trace_sched_switch_state() >> task_state_index() >> return 0; >> >> TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in >> the trace event. >> >> Prevent this by pushing the value read from __schedule() down the trace >> event. >> >> Reported-by: Abhijeet Dharmapurikar <adharmap@quicinc.com> >> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> >> --- >> include/linux/sched.h | 11 ++++++++--- >> include/trace/events/sched.h | 11 +++++++---- >> kernel/sched/core.c | 4 ++-- >> kernel/trace/fgraph.c | 4 +++- >> kernel/trace/ftrace.c | 4 +++- >> kernel/trace/trace_events.c | 8 ++++++-- >> kernel/trace/trace_sched_switch.c | 1 + > > I believe you may have missed some functions that register the sched_switch > event. Do a git grep on register_trace_sched_switch. >
Thanks! I'll wait a bit to see if anyone truly hates the idea and then will patch those up.
> -- Steve > > >> 7 files changed, 30 insertions(+), 13 deletions(-) >> >> diff --git a/include/linux/sched.h b/include/linux/sched.h >> index d2e261adb8ea..d00837d12b9d 100644
| |