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Commit 0cff784a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf: Optimize some swcounter attr.sample_period==1 paths 



Avoid the rather expensive perf_swevent_set_period() if we know
we have to sample every single event anyway.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091120212508.299508332@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 453f19ee

kernel/perf_event.c

+11 −6
Original line number Diff line number Diff line
@@ -3759,15 +3759,15 @@ static u64 perf_swevent_set_period(struct perf_event *event) 
	return nr;

}



static void perf_swevent_overflow(struct perf_event *event,

static void perf_swevent_overflow(struct perf_event *event, u64 overflow,

				    int nmi, struct perf_sample_data *data,

				    struct pt_regs *regs)

{

	struct hw_perf_event *hwc = &event->hw;

	int throttle = 0;

	u64 overflow;



	data->period = event->hw.last_period;

	if (!overflow)

		overflow = perf_swevent_set_period(event);



	if (hwc->interrupts == MAX_INTERRUPTS)
@@ -3801,14 +3801,19 @@ static void perf_swevent_add(struct perf_event *event, u64 nr, 


	atomic64_add(nr, &event->count);



	if (!regs)

		return;



	if (!hwc->sample_period)

		return;



	if (!regs)

	if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)

		return perf_swevent_overflow(event, 1, nmi, data, regs);



	if (atomic64_add_negative(nr, &hwc->period_left))

		return;



	if (!atomic64_add_negative(nr, &hwc->period_left))

		perf_swevent_overflow(event, nmi, data, regs);

	perf_swevent_overflow(event, 0, nmi, data, regs);

}



static int perf_swevent_is_counting(struct perf_event *event)