Messages in this thread | | | Subject | Re: [RFC 1/2] perf/core: Enable sched_task callbacks if PMU has it | From | "Liang, Kan" <> | Date | Thu, 5 Nov 2020 09:47:54 -0500 |
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On 11/2/2020 9:52 AM, Namhyung Kim wrote: > If an event associated with a PMU which has a sched_task callback, > it should be called regardless of cpu/task context. For example,
I don't think it's necessary. We should call it when we have to. Otherwise, it just waste cycles. Shouldn't the patch 2 be enough?
Thanks, Kan
> a per-cpu event might enable large PEBS buffers so it needs to flush > the buffer whenever task scheduling happens. > > The underlying PMU may or may not require this for the given event, > but it will be handled in the pmu::sched_task() callback anyway. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > kernel/events/core.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index b458ed3dc81b..aaa0155c4142 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4696,6 +4696,8 @@ static void unaccount_event(struct perf_event *event) > dec = true; > if (has_branch_stack(event)) > dec = true; > + if (event->pmu->sched_task) > + dec = true; > if (event->attr.ksymbol) > atomic_dec(&nr_ksymbol_events); > if (event->attr.bpf_event) > @@ -11225,6 +11227,8 @@ static void account_event(struct perf_event *event) > inc = true; > if (is_cgroup_event(event)) > inc = true; > + if (event->pmu->sched_task) > + inc = true; > if (event->attr.ksymbol) > atomic_inc(&nr_ksymbol_events); > if (event->attr.bpf_event) >
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