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-rw-r--r--arch/arm/include/asm/pmu.h2
-rw-r--r--arch/arm/kernel/perf_event.c22
-rw-r--r--arch/arm/kernel/perf_event_v6.c2
-rw-r--r--arch/arm/kernel/perf_event_v7.c2
-rw-r--r--arch/arm/kernel/perf_event_xscale.c4
5 files changed, 16 insertions, 16 deletions
diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index b5a5be2536c1..90114faa9f3c 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -134,7 +134,7 @@ int __init armpmu_register(struct arm_pmu *armpmu, char *name, int type);
u64 armpmu_event_update(struct perf_event *event,
struct hw_perf_event *hwc,
- int idx, int overflow);
+ int idx);
int armpmu_event_set_period(struct perf_event *event,
struct hw_perf_event *hwc,
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 5bb91bf3d47f..56173ae16448 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -180,7 +180,7 @@ armpmu_event_set_period(struct perf_event *event,
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;
@@ -193,13 +193,7 @@ again:
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);
@@ -216,7 +210,7 @@ armpmu_read(struct perf_event *event)
if (hwc->idx < 0)
return;
- armpmu_event_update(event, hwc, hwc->idx, 0);
+ armpmu_event_update(event, hwc, hwc->idx);
}
static void
@@ -232,7 +226,7 @@ armpmu_stop(struct perf_event *event, int flags)
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;
}
}
@@ -518,7 +512,13 @@ __hw_perf_event_init(struct perf_event *event)
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);
}
diff --git a/arch/arm/kernel/perf_event_v6.c b/arch/arm/kernel/perf_event_v6.c
index 533be9930ec2..88bf15253fbd 100644
--- a/arch/arm/kernel/perf_event_v6.c
+++ b/arch/arm/kernel/perf_event_v6.c
@@ -524,7 +524,7 @@ armv6pmu_handle_irq(int irq_num,
continue;
hwc = &event->hw;
- armpmu_event_update(event, hwc, idx, 1);
+ armpmu_event_update(event, hwc, idx);
data.period = event->hw.last_period;
if (!armpmu_event_set_period(event, hwc, idx))
continue;
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 6933244c68f9..6f488610f8fc 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -963,7 +963,7 @@ static irqreturn_t armv7pmu_handle_irq(int irq_num, void *dev)
continue;
hwc = &event->hw;
- armpmu_event_update(event, hwc, idx, 1);
+ armpmu_event_update(event, hwc, idx);
data.period = event->hw.last_period;
if (!armpmu_event_set_period(event, hwc, idx))
continue;
diff --git a/arch/arm/kernel/perf_event_xscale.c b/arch/arm/kernel/perf_event_xscale.c
index 3b99d8269829..831e019b017c 100644
--- a/arch/arm/kernel/perf_event_xscale.c
+++ b/arch/arm/kernel/perf_event_xscale.c
@@ -259,7 +259,7 @@ xscale1pmu_handle_irq(int irq_num, void *dev)
continue;
hwc = &event->hw;
- armpmu_event_update(event, hwc, idx, 1);
+ armpmu_event_update(event, hwc, idx);
data.period = event->hw.last_period;
if (!armpmu_event_set_period(event, hwc, idx))
continue;
@@ -596,7 +596,7 @@ xscale2pmu_handle_irq(int irq_num, void *dev)
continue;
hwc = &event->hw;
- armpmu_event_update(event, hwc, idx, 1);
+ armpmu_event_update(event, hwc, idx);
data.period = event->hw.last_period;
if (!armpmu_event_set_period(event, hwc, idx))
continue;