lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

perf_counter: Do not throttle single swcounter events

Browse Source 
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>
This commit is contained in:
Peter Zijlstra
2009-09-17 18:47:11 +02:00
committed by Ingo Molnar
parent 0ec04e16d0
commit 850bc73ffc
1 changed files with 13 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
kernel/perf_counter.c
View File

@@ -3494,14 +3494,15 @@ static void perf_log_throttle(struct perf_counter *counter, int enable)
* Generic counter overflow handling, sampling. * Generic counter overflow handling, sampling.
*/ */
int perf_counter_overflow(struct perf_counter *counter, int nmi, static int __perf_counter_overflow(struct perf_counter *counter, int nmi,
struct perf_sample_data *data) int throttle, struct perf_sample_data *data)
{ {
int events = atomic_read(&counter->event_limit); int events = atomic_read(&counter->event_limit);
int throttle = counter->pmu->unthrottle != NULL;
struct hw_perf_counter *hwc = &counter->hw; struct hw_perf_counter *hwc = &counter->hw;
int ret = 0; int ret = 0;
throttle = (throttle && counter->pmu->unthrottle != NULL);
if (!throttle) { if (!throttle) {
hwc->interrupts++; hwc->interrupts++;
} else { } else {
@@ -3554,6 +3555,12 @@ int perf_counter_overflow(struct perf_counter *counter, int nmi,
return ret; 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 * Generic software counter infrastructure
*/ */
@@ -3592,6 +3599,7 @@ static void perf_swcounter_overflow(struct perf_counter *counter,
int nmi, struct perf_sample_data *data) int nmi, struct perf_sample_data *data)
{ {
struct hw_perf_counter *hwc = &counter->hw; struct hw_perf_counter *hwc = &counter->hw;
int throttle = 0;
u64 overflow; u64 overflow;
data->period = counter->hw.last_period; data->period = counter->hw.last_period;
@@ -3601,13 +3609,14 @@ static void perf_swcounter_overflow(struct perf_counter *counter,
return; return;
for (; overflow; overflow--) { 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 * We inhibit the overflow from happening when
* hwc->interrupts == MAX_INTERRUPTS. * hwc->interrupts == MAX_INTERRUPTS.
*/ */
break; break;
} }
throttle = 0;
} }
} }