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

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

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20091120212508.299508332@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-11-20 22:19:44 +01:00 committed by Ingo Molnar
parent 453f19eea7
commit 0cff784ae4
1 changed files with 13 additions and 8 deletions
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21
kernel/perf_event.c
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@ -3759,16 +3759,16 @@ again:
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;
overflow = perf_swevent_set_period(event);
if (!overflow)
overflow = perf_swevent_set_period(event);
if (hwc->interrupts == MAX_INTERRUPTS)
return;
@ -3801,14 +3801,19 @@ static void perf_swevent_add(struct perf_event *event, u64 nr,
atomic64_add(nr, &event->count);
if (!hwc->sample_period)
return;
if (!regs)
return;
if (!atomic64_add_negative(nr, &hwc->period_left))
perf_swevent_overflow(event, nmi, data, regs);
if (!hwc->sample_period)
return;
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;
perf_swevent_overflow(event, 0, nmi, data, regs);
}
static int perf_swevent_is_counting(struct perf_event *event)