diff options
Diffstat (limited to 'arch/arm/kernel/perf_event.c')
| -rw-r--r-- | arch/arm/kernel/perf_event.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index f7c65adaa42..557e128e4df 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -116,8 +116,14 @@ int armpmu_event_set_period(struct perf_event *event) ret = 1; } - if (left > (s64)armpmu->max_period) - left = armpmu->max_period; + /* + * Limit the maximum period to prevent the counter value + * from overtaking the one we are about to program. In + * effect we are reducing max_period to account for + * interrupt latency (and we are being very conservative). + */ + if (left > (armpmu->max_period >> 1)) + left = armpmu->max_period >> 1; local64_set(&hwc->prev_count, (u64)-left); |