linux-kernel - [PATCH 1/2] perf: Enable wakeup

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Date:	Thu, 30 May 2013 11:53:06 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 1/2] perf: Enable wakeup_events logic for all events

Currently the perf_events_attr::wakeup_events logic is
checked only for regular samples.

If we have an event that produce only auxiliary events
(MMAP|COMM|EXIT|FORK), the poll call does not follow
the perf_events_attr wakeup_events setup and reports
no data.

Fixing this by moving the perf_events_attr::wakeup_events
checking logic into the function and calling it from
perf_output_end. This way any output event is checked
properly.

Signed-off-by: Jiri Olsa <jolsa@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Stephane Eranian <eranian@...gle.com>
---
 kernel/events/core.c        | 14 --------------
 kernel/events/ring_buffer.c | 20 ++++++++++++++++++++
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index a0780b3..516eb25 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4281,20 +4281,6 @@ void perf_output_sample(struct perf_output_handle *handle,
 		}
 	}
 
-	if (!event->attr.watermark) {
-		int wakeup_events = event->attr.wakeup_events;
-
-		if (wakeup_events) {
-			struct ring_buffer *rb = handle->rb;
-			int events = local_inc_return(&rb->events);
-
-			if (events >= wakeup_events) {
-				local_sub(wakeup_events, &rb->events);
-				local_inc(&rb->wakeup);
-			}
-		}
-	}
-
 	if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
 		if (data->br_stack) {
 			size_t size;
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index cd55144..1385fb1 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -54,6 +54,25 @@ static void perf_output_wakeup(struct perf_output_handle *handle)
 	irq_work_queue(&handle->event->pending);
 }
 
+static void perf_output_check_wakeup(struct perf_output_handle *handle)
+{
+	struct perf_event *event = handle->event;
+
+	if (!event->attr.watermark) {
+		int wakeup_events = event->attr.wakeup_events;
+
+		if (wakeup_events) {
+			struct ring_buffer *rb = handle->rb;
+			int events = local_inc_return(&rb->events);
+
+			if (events >= wakeup_events) {
+				local_sub(wakeup_events, &rb->events);
+				local_inc(&rb->wakeup);
+			}
+		}
+	}
+}
+
 /*
  * We need to ensure a later event_id doesn't publish a head when a former
  * event isn't done writing. However since we need to deal with NMIs we
@@ -208,6 +227,7 @@ unsigned int perf_output_skip(struct perf_output_handle *handle,
 
 void perf_output_end(struct perf_output_handle *handle)
 {
+	perf_output_check_wakeup(handle);
 	perf_output_put_handle(handle);
 	rcu_read_unlock();
 }
-- 
1.7.11.7

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