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perf: Convert perf_event to local_t

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Since now all modification to event->count (and ->prev_count
and ->period_left) are local to a cpu, change then to local64_t so we
avoid the LOCK'ed ops.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra
2010-05-21 14:43:08 +02:00
committed by Ingo Molnar
parent a6e6dea68c
commit e78505958c
7 changed files with 72 additions and 71 deletions
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18
arch/x86/kernel/cpu/perf_event.c
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@@ -296,10 +296,10 @@ x86_perf_event_update(struct perf_event *event)
* count to the generic event atomically:
*/
again:
prev_raw_count = atomic64_read(&hwc->prev_count);
prev_raw_count = local64_read(&hwc->prev_count);
rdmsrl(hwc->event_base + idx, new_raw_count);
if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
new_raw_count) != prev_raw_count)
goto again;
@@ -314,8 +314,8 @@ again:
delta = (new_raw_count << shift) - (prev_raw_count << shift);
delta >>= shift;
atomic64_add(delta, &event->count);
atomic64_sub(delta, &hwc->period_left);
local64_add(delta, &event->count);
local64_sub(delta, &hwc->period_left);
return new_raw_count;
}
@@ -439,7 +439,7 @@ static int x86_setup_perfctr(struct perf_event *event)
if (!hwc->sample_period) {
hwc->sample_period = x86_pmu.max_period;
hwc->last_period = hwc->sample_period;
atomic64_set(&hwc->period_left, hwc->sample_period);
local64_set(&hwc->period_left, hwc->sample_period);
} else {
/*
* If we have a PMU initialized but no APIC
@@ -886,7 +886,7 @@ static int
x86_perf_event_set_period(struct perf_event *event)
{
struct hw_perf_event *hwc = &event->hw;
s64 left = atomic64_read(&hwc->period_left);
s64 left = local64_read(&hwc->period_left);
s64 period = hwc->sample_period;
int ret = 0, idx = hwc->idx;
@@ -898,14 +898,14 @@ x86_perf_event_set_period(struct perf_event *event)
*/
if (unlikely(left <= -period)) {
left = period;
atomic64_set(&hwc->period_left, left);
local64_set(&hwc->period_left, left);
hwc->last_period = period;
ret = 1;
}
if (unlikely(left <= 0)) {
left += period;
atomic64_set(&hwc->period_left, left);
local64_set(&hwc->period_left, left);
hwc->last_period = period;
ret = 1;
}
@@ -924,7 +924,7 @@ x86_perf_event_set_period(struct perf_event *event)
* The hw event starts counting from this event offset,
* mark it to be able to extra future deltas:
*/
atomic64_set(&hwc->prev_count, (u64)-left);
local64_set(&hwc->prev_count, (u64)-left);
wrmsrl(hwc->event_base + idx, (u64)(-left) & x86_pmu.cntval_mask);