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| author | James Hogan <james.hogan@imgtec.com> | 2013-02-27 16:16:38 +0000 |
|---|---|---|
| committer | James Hogan <james.hogan@imgtec.com> | 2013-03-15 13:20:07 +0000 |
| commit | 2033dc54e6fffac01f6129c0038c2e78102cf59a (patch) | |
| tree | d5c674bec7f7d941ef70d430ed95144d793d9256 /arch | |
| parent | c6ac1e6edacc7e1fb0405d61f95a797c6a712411 (diff) | |
| download | linux-stable-2033dc54e6fffac01f6129c0038c2e78102cf59a.tar.gz linux-stable-2033dc54e6fffac01f6129c0038c2e78102cf59a.tar.bz2 linux-stable-2033dc54e6fffac01f6129c0038c2e78102cf59a.zip | |
metag: perf: fix frequency sampling (dynamic period)
Frequency sampling mode dynamically adjusts the sample period so as to
hit a particular frequency of samples. The sample period starts at just
1 and then gets increased if the interrupt rate is too high. This
changed sample period needs handling in metag_pmu_event_set_period to
update period_left (as the ARM equivalent does). The calculated delta
also needs subtracting from period_left in metag_pmu_event_update in
order to hit the conditional blocks in metag_pmu_event_set_period which
update last_period (which is used in the dynamic sampling period
calculation).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/metag/kernel/perf/perf_event.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/metag/kernel/perf/perf_event.c b/arch/metag/kernel/perf/perf_event.c index 5bf984feaaa1..6210126de78a 100644 --- a/arch/metag/kernel/perf/perf_event.c +++ b/arch/metag/kernel/perf/perf_event.c @@ -214,6 +214,7 @@ again: delta = (new_raw_count - prev_raw_count) & MAX_PERIOD; local64_add(delta, &event->count); + local64_sub(delta, &hwc->period_left); } int metag_pmu_event_set_period(struct perf_event *event, @@ -223,6 +224,10 @@ int metag_pmu_event_set_period(struct perf_event *event, s64 period = hwc->sample_period; int ret = 0; + /* The period may have been changed */ + if (unlikely(period != hwc->last_period)) + left += period - hwc->last_period; + if (unlikely(left <= -period)) { left = period; local64_set(&hwc->period_left, left); |