[PATCH V3 3/6] perf/x86: implement overhead stat for x86 pmu

[kan . liang]

From: Kan Liang <kan.li...@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.li...@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