Messages in this thread |  | | Subject | Re: [PATCH v5 1/3] perf/core: store context switch out type into Perf trace | From | Alexey Budankov <> | Date | Mon, 9 Apr 2018 12:56:00 +0300 |
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On 09.04.2018 12:26, Peter Zijlstra wrote: > On Mon, Apr 09, 2018 at 10:25:32AM +0300, Alexey Budankov wrote: >> >> Store preempting context switch out event into Perf trace as a part of >> PERF_RECORD_SWITCH[_CPU_WIDE] record. >> >> Percentage of preempting and non-preempting context switches help >> understanding the nature of workloads (CPU or IO bound) that are running >> on a machine; >> >> The event is treated as preemption one when task->state value of the >> thread being switched out is TASK_RUNNING. Event type encoding is >> implemented using PERF_RECORD_MISC_SWITCH_OUT_PREEMPT bit; >> >> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> > > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > Acme, I'm thinking you should route this, since most of the changes are > actually to the tool. > >> diff --git a/kernel/events/core.c b/kernel/events/core.c >> index fc1c330c6bd6..872a5aaa77eb 100644 >> --- a/kernel/events/core.c >> +++ b/kernel/events/core.c >> @@ -7584,6 +7584,10 @@ static void perf_event_switch(struct task_struct *task, >> }, >> }; >> >> + if (!sched_in && task->state == TASK_RUNNING) >> + switch_event.event_id.header.misc |= >> + PERF_RECORD_MISC_SWITCH_OUT_PREEMPT; > > I typically prefer {} over any multi-line expression.
Yep, makes sense. Sorry for missing that here.
> >> perf_iterate_sb(perf_event_switch_output, >> &switch_event, >> NULL); >
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