From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>,
Corey Ashford <cjashfor@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] perf_counter: optimize mmap/comm tracking
Date: Thu, 09 Apr 2009 11:28:29 +0200 [thread overview]
Message-ID: <1239269309.7647.196.camel@twins> (raw)
In-Reply-To: <20090409091622.GA23636@elte.hu>
On Thu, 2009-04-09 at 11:16 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> > +static atomic_t nr_comm_tracking __read_mostly;
>
> hm, nr_comm_tracking is not actually used by any fastpath - just
> increased and then decreased.
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -2018,7 +2018,12 @@ static void perf_counter_comm_event(stru
void perf_counter_comm(struct task_struct *task)
{
- struct perf_comm_event comm_event = {
+ struct perf_comm_event comm_event;
+
+ if (!atomic_read(&nr_comm_tracking))
+ return;
+
+ comm_event = (struct perf_comm_event){
.task = task,
.event = {
.header = { .type = PERF_EVENT_COMM, },
next prev parent reply other threads:[~2009-04-09 9:26 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-09 8:53 [PATCH 0/4] perf_counter: fixes and an optimization Peter Zijlstra
2009-04-09 8:53 ` [PATCH 1/4] perf_counter: fix off-by-one on the string lengths Peter Zijlstra
2009-04-09 8:53 ` [PATCH 2/4] perf_counter: optimize mmap/comm tracking Peter Zijlstra
2009-04-09 9:06 ` [tip:perfcounters/core] " Peter Zijlstra
2009-04-09 9:16 ` [PATCH 2/4] " Ingo Molnar
2009-04-09 9:28 ` Peter Zijlstra [this message]
2009-04-09 9:54 ` [tip:perfcounters/core] " Peter Zijlstra
2009-04-09 8:53 ` [PATCH 3/4] perf_counter: sysctl for system wide perf counters Peter Zijlstra
2009-04-09 9:06 ` [tip:perfcounters/core] " Peter Zijlstra
2009-04-09 9:54 ` Peter Zijlstra
2009-04-09 8:53 ` [PATCH 4/4] perf_counter: log full path names Peter Zijlstra
2009-04-09 9:07 ` [tip:perfcounters/core] " Peter Zijlstra
2009-04-09 9:54 ` Peter Zijlstra
2009-04-09 9:03 ` [PATCH 0/4] perf_counter: fixes and an optimization Ingo Molnar
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