From: Ingo Molnar <mingo@elte.hu>
To: "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
"Frédéric Weisbecker" <fweisbec@gmail.com>
Cc: Andrew Steets <asteets@rgmadvisors.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Subject: Re: perf: prctl(PR_TASK_PERF_EVENTS_DISABLE) has no effect
Date: Mon, 30 Jan 2012 11:11:21 +0100 [thread overview]
Message-ID: <20120130101121.GB8924@elte.hu> (raw)
In-Reply-To: <1327917156.2446.191.camel@twins>
* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> On Sun, 2012-01-29 at 17:32 +0100, Ingo Molnar wrote:
> > * Andrew Steets <asteets@rgmadvisors.com> wrote:
> >
> > > On 1/28/12 6:01 AM, Ingo Molnar wrote:
> > >
> > > >> prctl(PR_TASK_PERF_EVENTS_DISABLE) doesn't appear to
> > > >> disable perf event counters. Here is a demonstration
> > > >> program:
> > > >
> > > > btw., what's your usecase?
> > >
> > > I'm trying to profile a small section of a long-running
> > > program. I ran into trouble using call-graph recording
> > > and I thought this might be an alternative way of getting
> > > what I was after.
> >
> > That usecase indeed makes sense. Peter, could we allow this
> > for privileged tasks, depending on the perf_paranoia
> > settings or such?
>
> I really dislike it. The sane way around this would be to
> allow easy self-profiling instead of doing things arse about
> face like that.
So, what workflow are you suggesting to Andrew?
I guess we are also hurting from the lack of dwarf stack
backtrace decoding - that would allow the filtering by parent
function without modifying the code. I think Frederic had a
prototype working for 32-bit - any update on that?
Andrew could work that problem around right now by adding:
-fno-omit-frame-pointer
to the build of the utility - that should activate -g and
perf-report's --parent filter should also work fine.
Thanks,
Ingo
next prev parent reply other threads:[~2012-01-30 10:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 17:03 perf: prctl(PR_TASK_PERF_EVENTS_DISABLE) has no effect Andrew Steets
2012-01-27 17:12 ` Peter Zijlstra
2012-01-27 20:06 ` Andrew Steets
2012-01-27 21:34 ` Peter Zijlstra
2012-01-28 12:01 ` Ingo Molnar
2012-01-28 23:48 ` Andrew Steets
2012-01-29 16:32 ` Ingo Molnar
2012-01-29 17:50 ` Gleb Natapov
2012-01-30 9:52 ` Peter Zijlstra
2012-01-30 10:11 ` Ingo Molnar [this message]
2012-01-30 11:01 ` Peter Zijlstra
2012-01-30 11:31 ` Ingo Molnar
2012-01-30 13:45 ` Peter Zijlstra
2012-01-30 13:58 ` Ingo Molnar
2012-01-30 15:30 ` Arnaldo Carvalho de Melo
2012-01-30 15:29 ` Arnaldo Carvalho de Melo
2012-02-01 19:03 ` Frederic Weisbecker
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