From: kan.liang@intel.com
To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
linux-kernel@vger.kernel.org
Cc: alexander.shishkin@linux.intel.com, tglx@linutronix.de,
namhyung@kernel.org, jolsa@kernel.org, adrian.hunter@intel.com,
wangnan0@huawei.com, mark.rutland@arm.com, andi@firstfloor.org,
Kan Liang <kan.liang@intel.com>
Subject: [PATCH V3 5/6] perf/core: calculate side-band events overhead
Date: Thu, 8 Dec 2016 16:27:13 -0500 [thread overview]
Message-ID: <1481232434-3574-6-git-send-email-kan.liang@intel.com> (raw)
In-Reply-To: <1481232434-3574-1-git-send-email-kan.liang@intel.com>
From: Kan Liang <kan.liang@intel.com>
Iterating all events which need to receive side-band events also bring
some overhead.
The side-band events overhead PERF_CORE_SB_OVERHEAD is a common overhead
type.
Signed-off-by: Kan Liang <kan.liang@intel.com>
---
include/uapi/linux/perf_event.h | 1 +
kernel/events/core.c | 17 ++++++++++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index c488336..7ba6d30 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -1002,6 +1002,7 @@ struct perf_branch_entry {
enum perf_record_overhead_type {
/* common overhead */
PERF_CORE_MUX_OVERHEAD = 0,
+ PERF_CORE_SB_OVERHEAD,
/* PMU specific */
PERF_OVERHEAD_MAX,
};
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 28468ae..335b1e2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6134,9 +6134,13 @@ 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_cpu_context *cpuctx;
struct perf_event_context *ctx;
+ u64 start_clock, end_clock;
int ctxn;
+ start_clock = perf_clock();
rcu_read_lock();
preempt_disable();
@@ -6154,12 +6158,23 @@ 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();
+
+ /* calculate side-band event overhead */
+ end_clock = perf_clock();
+ if (overhead_ctx && overhead_ctx->pmu && overhead_ctx->pmu->stat) {
+ cpuctx = this_cpu_ptr(overhead_ctx->pmu->pmu_cpu_context);
+ cpuctx->overhead[PERF_CORE_SB_OVERHEAD].nr++;
+ cpuctx->overhead[PERF_CORE_SB_OVERHEAD].time += end_clock - start_clock;
+ }
}
/*
--
2.4.3
next prev parent reply other threads:[~2016-12-08 21:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-08 21:27 [PATCH V3 0/6] export perf overheads information (kernel) kan.liang
2016-12-08 21:27 ` [PATCH V3 1/6] perf/core: Introduce PERF_RECORD_OVERHEAD kan.liang
2016-12-08 21:27 ` [PATCH V3 2/6] perf/core: Add PERF_EVENT_IOC_STAT to control overhead statistics kan.liang
2016-12-08 21:27 ` [PATCH V3 3/6] perf/x86: implement overhead stat for x86 pmu kan.liang
2016-12-08 21:27 ` [PATCH V3 4/6] perf/core: calculate multiplexing overhead kan.liang
2016-12-08 21:27 ` kan.liang [this message]
2016-12-08 21:27 ` [PATCH V3 6/6] perf/x86: calculate sampling overhead kan.liang
2016-12-16 15:08 ` [PATCH V3 0/6] export perf overheads information (kernel) Liang, Kan
2017-01-06 15:25 ` Liang, Kan
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