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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-09-17 18:47:11 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-17 22:08:25 +0200 |
| commit | 850bc73ffcc99cddfb52bc23217c60810c508853 (patch) | |
| tree | 787a863ccb2aaa1de48a6690b33026beadecce20 /kernel/perf_counter.c | |
| parent | 0ec04e16d08b69d8da46abbcfa3e3f2cd9738852 (diff) | |
| download | lwn-850bc73ffcc99cddfb52bc23217c60810c508853.tar.gz lwn-850bc73ffcc99cddfb52bc23217c60810c508853.zip | |
perf_counter: Do not throttle single swcounter events
We can have swcounter events that contribute more than a single
count per event, when used with a non-zero period, those can
generate multiple events, which is when we need throttling.
However, swcounter that contribute only a single count per event
can only come as fast as we can run code, hence don't throttle
them.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
| -rw-r--r-- | kernel/perf_counter.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 667ab25ad3d5..fe0d1adde804 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -3494,14 +3494,15 @@ static void perf_log_throttle(struct perf_counter *counter, int enable) * Generic counter overflow handling, sampling. */ -int perf_counter_overflow(struct perf_counter *counter, int nmi, - struct perf_sample_data *data) +static int __perf_counter_overflow(struct perf_counter *counter, int nmi, + int throttle, struct perf_sample_data *data) { int events = atomic_read(&counter->event_limit); - int throttle = counter->pmu->unthrottle != NULL; struct hw_perf_counter *hwc = &counter->hw; int ret = 0; + throttle = (throttle && counter->pmu->unthrottle != NULL); + if (!throttle) { hwc->interrupts++; } else { @@ -3554,6 +3555,12 @@ int perf_counter_overflow(struct perf_counter *counter, int nmi, return ret; } +int perf_counter_overflow(struct perf_counter *counter, int nmi, + struct perf_sample_data *data) +{ + return __perf_counter_overflow(counter, nmi, 1, data); +} + /* * Generic software counter infrastructure */ @@ -3592,6 +3599,7 @@ static void perf_swcounter_overflow(struct perf_counter *counter, int nmi, struct perf_sample_data *data) { struct hw_perf_counter *hwc = &counter->hw; + int throttle = 0; u64 overflow; data->period = counter->hw.last_period; @@ -3601,13 +3609,14 @@ static void perf_swcounter_overflow(struct perf_counter *counter, return; for (; overflow; overflow--) { - if (perf_counter_overflow(counter, nmi, data)) { + if (__perf_counter_overflow(counter, nmi, throttle, data)) { /* * We inhibit the overflow from happening when * hwc->interrupts == MAX_INTERRUPTS. */ break; } + throttle = 0; } } |