u64
armpmu_event_update(struct perf_event *event,
struct hw_perf_event *hwc,
- int idx, int overflow)
+ int idx)
{
struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
u64 delta, prev_raw_count, new_raw_count;
new_raw_count) != prev_raw_count)
goto again;
- new_raw_count &= armpmu->max_period;
- prev_raw_count &= armpmu->max_period;
-
- if (overflow)
- delta = armpmu->max_period - prev_raw_count + new_raw_count + 1;
- else
- delta = new_raw_count - prev_raw_count;
+ delta = (new_raw_count - prev_raw_count) & armpmu->max_period;
local64_add(delta, &event->count);
local64_sub(delta, &hwc->period_left);
if (hwc->idx < 0)
return;
- armpmu_event_update(event, hwc, hwc->idx, 0);
+ armpmu_event_update(event, hwc, hwc->idx);
}
static void
if (!(hwc->state & PERF_HES_STOPPED)) {
armpmu->disable(hwc, hwc->idx);
barrier(); /* why? */
- armpmu_event_update(event, hwc, hwc->idx, 0);
+ armpmu_event_update(event, hwc, hwc->idx);
hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
}
}
hwc->config_base |= (unsigned long)mapping;
if (!hwc->sample_period) {
- hwc->sample_period = armpmu->max_period;
+ /*
+ * For non-sampling runs, limit the sample_period to half
+ * of the counter width. That way, the new counter value
+ * is far less likely to overtake the previous one unless
+ * you have some serious IRQ latency issues.
+ */
+ hwc->sample_period = armpmu->max_period >> 1;
hwc->last_period = hwc->sample_period;
local64_set(&hwc->period_left, hwc->sample_period);
}