Perf: Save and restore counters through powercollapse
Update the active perf counter data structs with the most recent
values of the counters before going into powercollapse and restore
the corresponding hardware counters with these values when coming
out of it.
This change fixes a bug where the counter outputs show wild swings
when CPU power collapse is enabled.
Change-Id: I9c4ff4d4504df5b50c33a796c605126448c440cb
Signed-off-by: Ashwin Chaugule <ashwinc@codeaurora.org>
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index b59ad93..6a7158b 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -247,7 +247,6 @@
/* Don't read disabled counters! */
if (hwc->idx < 0)
return;
-
armpmu_event_update(event, hwc, hwc->idx, 0);
}
@@ -632,6 +631,24 @@
armpmu->stop();
}
+static void armpmu_update_counters(void)
+{
+ int idx;
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+
+ if (!armpmu)
+ return;
+
+ for (idx = 0; idx <= armpmu->num_events; ++idx) {
+ struct perf_event *event = cpuc->events[idx];
+
+ if (!event)
+ continue;
+
+ armpmu_read(event);
+ }
+}
+
static struct pmu pmu = {
.pmu_enable = armpmu_enable,
.pmu_disable = armpmu_disable,
@@ -657,6 +674,7 @@
{
switch (cmd) {
case CPU_PM_ENTER:
+ armpmu_update_counters();
perf_pmu_disable(&pmu);
break;
diff --git a/arch/arm/kernel/perf_event_msm.c b/arch/arm/kernel/perf_event_msm.c
index b40a226..8fa2f30 100644
--- a/arch/arm/kernel/perf_event_msm.c
+++ b/arch/arm/kernel/perf_event_msm.c
@@ -610,6 +610,7 @@
u32 gr;
unsigned long event;
struct scorpion_evt evtinfo;
+ unsigned long long prev_count = local64_read(&hwc->prev_count);
/*
* Enable counter and interrupt, and set the counter to count
@@ -652,6 +653,9 @@
/* Enable interrupt for this counter */
armv7_pmnc_enable_intens(idx);
+ /* Restore prev val */
+ armv7pmu_write_counter(idx, prev_count & COUNT_MASK);
+
/* Enable counter */
armv7_pmnc_enable_counter(idx);
diff --git a/arch/arm/kernel/perf_event_msm_krait.c b/arch/arm/kernel/perf_event_msm_krait.c
index cf1f1ee..3c8fb84 100644
--- a/arch/arm/kernel/perf_event_msm_krait.c
+++ b/arch/arm/kernel/perf_event_msm_krait.c
@@ -419,6 +419,7 @@
u32 gr;
unsigned long event;
struct krait_evt evtinfo;
+ unsigned long long prev_count = local64_read(&hwc->prev_count);
/*
* Enable counter and interrupt, and set the counter to count
@@ -465,6 +466,9 @@
/* Enable interrupt for this counter */
armv7_pmnc_enable_intens(idx);
+ /* Restore prev val */
+ armv7pmu_write_counter(idx, prev_count & COUNT_MASK);
+
/* Enable counter */
armv7_pmnc_enable_counter(idx);
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 277f1ce..3689e07 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -738,6 +738,10 @@
#define ARMV7_EXCLUDE_USER (1 << 30)
#define ARMV7_INCLUDE_HYP (1 << 27)
+
+/* Mask for restoring h/w counter val */
+#define COUNT_MASK 0xffffffff
+
/*
* Add an event filter to a given event. This will only work for PMUv2 PMUs.
*/