linux-kernel - [PATCH] perf: Don't schedule tracepoints when exclude

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Date:	Fri,  8 Apr 2011 22:57:55 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: [PATCH] perf: Don't schedule tracepoints when exclude_kernel is set

Instead of checking attr.exclude_kernel anytime a tracepoint
event triggers, simply don't schedule the tracepoint it that
attribute is set. This makes one test less in the tracing
path.

Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Stephane Eranian <eranian@...gle.com>
---
 kernel/perf_event.c             |    5 -----
 kernel/trace/trace_event_perf.c |    6 +++++-
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index c75925c..2f3fb90 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5491,11 +5491,6 @@ static int perf_tp_event_match(struct perf_event *event,
 {
 	if (event->hw.state & PERF_HES_STOPPED)
 		return 0;
-	/*
-	 * All tracepoints are from kernel-space.
-	 */
-	if (event->attr.exclude_kernel)
-		return 0;
 
 	if (!perf_tp_filter_match(event, data))
 		return 0;
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 19a359d..427314b 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -136,6 +136,10 @@ int perf_trace_add(struct perf_event *p_event, int flags)
 	struct hlist_head __percpu *pcpu_list;
 	struct hlist_head *list;
 
+	/* Tracepoints always trigger in the kernel */
+	if (p_event->attr.exclude_kernel)
+		return 0;
+
 	pcpu_list = tp_event->perf_events;
 	if (WARN_ON_ONCE(!pcpu_list))
 		return -EINVAL;
@@ -151,7 +155,7 @@ int perf_trace_add(struct perf_event *p_event, int flags)
 
 void perf_trace_del(struct perf_event *p_event, int flags)
 {
-	hlist_del_rcu(&p_event->hlist_entry);
+	hlist_del_init_rcu(&p_event->hlist_entry);
 }
 
 void perf_trace_destroy(struct perf_event *p_event)
-- 
1.7.3.2

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