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Subject[PATCH V3 3/6] perf/x86: implement overhead stat for x86 pmu
Date
From: Kan Liang <kan.liang@intel.com>

In STAT_START, resets overhead counter for each possible cpuctx of event
pmu.
In STAT_DONE, generate overhead information for each possible cpuctx and
reset the overhead counteris.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
arch/x86/events/core.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 6e395c9..09ab36a 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2198,6 +2198,40 @@ static void x86_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
x86_pmu.sched_task(ctx, sched_in);
}

+static int x86_pmu_stat(struct perf_event *event, u32 flag)
+{
+ struct perf_cpu_context *cpuctx;
+ struct pmu *pmu = event->pmu;
+ int cpu, i;
+
+ if (!(flag & (PERF_IOC_FLAG_STAT_START | PERF_IOC_FLAG_STAT_DONE)))
+ return -EINVAL;
+
+ if (!event->attr.overhead)
+ return -EINVAL;
+
+ if (flag & PERF_IOC_FLAG_STAT_DONE) {
+ for_each_possible_cpu(cpu) {
+ cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+
+ for (i = 0; i < PERF_OVERHEAD_MAX; i++) {
+ if (!cpuctx->overhead[i].nr)
+ continue;
+ perf_log_overhead(event, i, cpu,
+ cpuctx->overhead[i].nr,
+ cpuctx->overhead[i].time);
+ }
+ }
+ }
+
+ for_each_possible_cpu(cpu) {
+ cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+ memset(cpuctx->overhead, 0, PERF_OVERHEAD_MAX * sizeof(struct perf_overhead_entry));
+ }
+
+ return 0;
+}
+
void perf_check_microcode(void)
{
if (x86_pmu.check_microcode)
@@ -2228,6 +2262,9 @@ static struct pmu pmu = {

.event_idx = x86_pmu_event_idx,
.sched_task = x86_pmu_sched_task,
+
+ .stat = x86_pmu_stat,
+
.task_ctx_size = sizeof(struct x86_perf_task_context),
};

--
2.4.3
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