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Groups > linux.kernel > #1528647

[PATCH 04/14] perf/x86: output side-band events overhead

From kan.liang@intel.com
Newsgroups linux.kernel
Subject [PATCH 04/14] perf/x86: output side-band events overhead
Date 2016-11-23 18:50 +0100
Message-ID <sGJQe-7SF-19@gated-at.bofh.it> (permalink)
References <sGJQd-7SF-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Kan Liang <kan.liang@intel.com>

Iterating all events which need to receive side-band events also bring
some overhead.
Save the overhead information in task context or CPU context, whichever
context is available.

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
 include/linux/perf_event.h      |  2 ++
 include/uapi/linux/perf_event.h |  1 +
 kernel/events/core.c            | 32 ++++++++++++++++++++++++++++----
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f72b97a..ec3cb7f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -764,6 +764,8 @@ struct perf_event_context {
 #endif
 	void				*task_ctx_data; /* pmu specific data */
 	struct rcu_head			rcu_head;
+
+	struct perf_overhead_entry	sb_overhead;
 };
 
 /*
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 9124c7c..5e7c522 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -994,6 +994,7 @@ struct perf_branch_entry {
 enum perf_record_overhead_type {
 	PERF_NMI_OVERHEAD	= 0,
 	PERF_MUX_OVERHEAD,
+	PERF_SB_OVERHEAD,
 
 	PERF_OVERHEAD_MAX,
 };
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 9934059..51e9df7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1829,9 +1829,15 @@ event_sched_out(struct perf_event *event,
 	if (event->attr.exclusive || !cpuctx->active_oncpu)
 		cpuctx->exclusive = 0;
 
-	if (log_overhead && cpuctx->mux_overhead.nr) {
-		cpuctx->mux_overhead.cpu = smp_processor_id();
-		perf_log_overhead(event, PERF_MUX_OVERHEAD, &cpuctx->mux_overhead);
+	if (log_overhead) {
+		if (cpuctx->mux_overhead.nr) {
+			cpuctx->mux_overhead.cpu = smp_processor_id();
+			perf_log_overhead(event, PERF_MUX_OVERHEAD, &cpuctx->mux_overhead);
+		}
+		if (ctx->sb_overhead.nr) {
+			ctx->sb_overhead.cpu = smp_processor_id();
+			perf_log_overhead(event, PERF_SB_OVERHEAD, &ctx->sb_overhead);
+		}
 	}
 
 	perf_pmu_enable(event->pmu);
@@ -6133,6 +6139,14 @@ static void perf_iterate_sb_cpu(perf_iterate_f output, void *data)
 	}
 }
 
+static void
+perf_caculate_sb_overhead(struct perf_event_context *ctx,
+			  u64 time)
+{
+	ctx->sb_overhead.nr++;
+	ctx->sb_overhead.time += time;
+}
+
 /*
  * Iterate all events that need to receive side-band events.
  *
@@ -6143,9 +6157,12 @@ static void
 perf_iterate_sb(perf_iterate_f output, void *data,
 	       struct perf_event_context *task_ctx)
 {
+	struct perf_event_context *overhead_ctx = task_ctx;
 	struct perf_event_context *ctx;
+	u64 start_clock, end_clock;
 	int ctxn;
 
+	start_clock = perf_clock();
 	rcu_read_lock();
 	preempt_disable();
 
@@ -6163,12 +6180,19 @@ perf_iterate_sb(perf_iterate_f output, void *data,
 
 	for_each_task_context_nr(ctxn) {
 		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
-		if (ctx)
+		if (ctx) {
 			perf_iterate_ctx(ctx, output, data, false);
+			if (!overhead_ctx)
+				overhead_ctx = ctx;
+		}
 	}
 done:
 	preempt_enable();
 	rcu_read_unlock();
+
+	end_clock = perf_clock();
+	if (overhead_ctx)
+		perf_caculate_sb_overhead(overhead_ctx, end_clock - start_clock);
 }
 
 /*
-- 
2.5.5

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[PATCH 00/14] export perf overheads information kan.liang@intel.com - 2016-11-23 18:50 +0100
  [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Peter Zijlstra <peterz@infradead.org> - 2016-11-23 21:20 +0100
    Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Peter Zijlstra <peterz@infradead.org> - 2016-11-23 21:20 +0100
    Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:50 +0100
      RE: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD "Liang, Kan" <kan.liang@intel.com> - 2016-11-24 14:50 +0100
        Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Peter Zijlstra <peterz@infradead.org> - 2016-11-24 15:00 +0100
          RE: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD "Liang, Kan" <kan.liang@intel.com> - 2016-11-24 15:10 +0100
            Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Jiri Olsa <jolsa@redhat.com> - 2016-11-24 15:30 +0100
              Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Jiri Olsa <jolsa@redhat.com> - 2016-11-24 15:50 +0100
              RE: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD "Liang, Kan" <kan.liang@intel.com> - 2016-11-24 15:50 +0100
          Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Andi Kleen <andi@firstfloor.org> - 2016-11-24 19:30 +0100
            Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Peter Zijlstra <peterz@infradead.org> - 2016-11-24 20:00 +0100
              Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Andi Kleen <andi@firstfloor.org> - 2016-11-24 20:10 +0100
                Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD Peter Zijlstra <peterz@infradead.org> - 2016-11-24 20:10 +0100
  [PATCH 11/14] perf tools: record write data overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 11/14] perf tools: record write data overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:10 +0100
    Re: [PATCH 11/14] perf tools: record write data overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:20 +0100
  [PATCH 04/14] perf/x86: output side-band events overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 04/14] perf/x86: output side-band events overhead Peter Zijlstra <peterz@infradead.org> - 2016-11-23 21:10 +0100
    Re: [PATCH 04/14] perf/x86: output side-band events overhead Mark Rutland <mark.rutland@arm.com> - 2016-11-24 17:30 +0100
      RE: [PATCH 04/14] perf/x86: output side-band events overhead "Liang, Kan" <kan.liang@intel.com> - 2016-11-24 20:50 +0100
  [PATCH 07/14] perf tools: show multiplexing overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
  [PATCH 08/14] perf tools: show side-band events overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
  [PATCH 05/14] perf tools: handle PERF_RECORD_OVERHEAD record type kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 05/14] perf tools: handle PERF_RECORD_OVERHEAD record type Jiri Olsa <jolsa@redhat.com> - 2016-11-23 23:40 +0100
      Re: [PATCH 05/14] perf tools: handle PERF_RECORD_OVERHEAD record type Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:00 +0100
  [PATCH 12/14] perf tools: record elapsed time kan.liang@intel.com - 2016-11-23 18:50 +0100
  [PATCH 13/14] perf tools: warn on high overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 13/14] perf tools: warn on high overhead Andi Kleen <andi@firstfloor.org> - 2016-11-23 21:30 +0100
      RE: [PATCH 13/14] perf tools: warn on high overhead "Liang, Kan" <kan.liang@intel.com> - 2016-11-23 23:10 +0100
  [PATCH 14/14] perf script: show overhead events kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 14/14] perf script: show overhead events Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:30 +0100
    Re: [PATCH 14/14] perf script: show overhead events Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:30 +0100
    Re: [PATCH 14/14] perf script: show overhead events Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:40 +0100
    Re: [PATCH 14/14] perf script: show overhead events Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:40 +0100
  [PATCH 03/14] perf/x86: output multiplexing overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 03/14] perf/x86: output multiplexing overhead Peter Zijlstra <peterz@infradead.org> - 2016-11-23 21:10 +0100
      RE: [PATCH 03/14] perf/x86: output multiplexing overhead "Liang, Kan" <kan.liang@intel.com> - 2016-11-23 21:20 +0100
  [PATCH 10/14] perf tools: introduce PERF_RECORD_USER_OVERHEAD kan.liang@intel.com - 2016-11-23 18:50 +0100
  [PATCH 06/14] perf tools: show NMI overhead kan.liang@intel.com - 2016-11-23 18:50 +0100
    Re: [PATCH 06/14] perf tools: show NMI overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:00 +0100
    Re: [PATCH 06/14] perf tools: show NMI overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:00 +0100
      RE: [PATCH 06/14] perf tools: show NMI overhead "Liang, Kan" <kan.liang@intel.com> - 2016-11-24 14:40 +0100
        Re: [PATCH 06/14] perf tools: show NMI overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 16:30 +0100
          Re: [PATCH 06/14] perf tools: show NMI overhead Namhyung Kim <namhyung@kernel.org> - 2016-11-25 00:30 +0100
            Re: [PATCH 06/14] perf tools: show NMI overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-25 00:50 +0100
          Re: [PATCH 06/14] perf tools: show NMI overhead Andi Kleen <andi@firstfloor.org> - 2016-11-25 01:30 +0100
    Re: [PATCH 06/14] perf tools: show NMI overhead Jiri Olsa <jolsa@redhat.com> - 2016-11-24 00:00 +0100
  Re: [PATCH 00/14] export perf overheads information Ingo Molnar <mingo@kernel.org> - 2016-11-24 05:30 +0100

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