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perf_counter: Fix frequency adjustment for < HZ

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Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-06-05 18:01:29 +02:00 committed by Ingo Molnar
parent 689802b2d0
commit 6a24ed6c60
2 changed files with 28 additions and 7 deletions
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3
include/linux/perf_counter.h
View file

@ -373,6 +373,9 @@ struct hw_perf_counter {
u64 sample_period;
atomic64_t period_left;
u64 interrupts;
u64 freq_count;
u64 freq_interrupts;
#endif
};

32
kernel/perf_counter.c
View file

@ -1187,8 +1187,9 @@ static void perf_log_period(struct perf_counter *counter, u64 period);
static void perf_adjust_freq(struct perf_counter_context *ctx)
{
struct perf_counter *counter;
struct hw_perf_counter *hwc;
u64 interrupts, sample_period;
u64 events, period;
u64 events, period, freq;
s64 delta;
spin_lock(&ctx->lock);
@ -1196,8 +1197,10 @@ static void perf_adjust_freq(struct perf_counter_context *ctx)
if (counter->state != PERF_COUNTER_STATE_ACTIVE)
continue;
interrupts = counter->hw.interrupts;
counter->hw.interrupts = 0;
hwc = &counter->hw;
interrupts = hwc->interrupts;
hwc->interrupts = 0;
if (interrupts == MAX_INTERRUPTS) {
perf_log_throttle(counter, 1);
@ -1208,20 +1211,35 @@ static void perf_adjust_freq(struct perf_counter_context *ctx)
if (!counter->attr.freq || !counter->attr.sample_freq)
continue;
events = HZ * interrupts * counter->hw.sample_period;
if (counter->attr.sample_freq < HZ) {
freq = counter->attr.sample_freq;
hwc->freq_count += freq;
hwc->freq_interrupts += interrupts;
if (hwc->freq_count < HZ)
continue;
interrupts = hwc->freq_interrupts;
hwc->freq_interrupts = 0;
hwc->freq_count -= HZ;
} else
freq = HZ;
events = freq * interrupts * hwc->sample_period;
period = div64_u64(events, counter->attr.sample_freq);
delta = (s64)(1 + period - counter->hw.sample_period);
delta = (s64)(1 + period - hwc->sample_period);
delta >>= 1;
sample_period = counter->hw.sample_period + delta;
sample_period = hwc->sample_period + delta;
if (!sample_period)
sample_period = 1;
perf_log_period(counter, sample_period);
counter->hw.sample_period = sample_period;
hwc->sample_period = sample_period;
}
spin_unlock(&ctx->lock);
}