linux-kernel - Re: [PATCH 1/1 v2] perf record: We should fork only if a program was specified to run

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Message-ID: <1261260207.4314.4.camel@laptop>
Date:	Sat, 19 Dec 2009 23:03:27 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH 1/1 v2] perf record: We should fork only if a program
 was specified to run

On Sat, 2009-12-19 at 19:58 -0200, Arnaldo Carvalho de Melo wrote:
> Em Sat, Dec 19, 2009 at 10:39:01PM +0100, Peter Zijlstra escreveu:
> > On Sat, 2009-12-19 at 19:22 -0200, Arnaldo Carvalho de Melo wrote:
> > > @@ -550,7 +551,7 @@ static int __cmd_record(int argc __used, const char **argv)
> > >                         return err;
> > >         }
> > >  
> > > -       if (!system_wide)
> > > +       if (!system_wide && profile_cpu == -1)
> > >                 event__synthesize_thread(pid, process_synthesized_event,
> > >                                          session); 
> > 
> > Not actually sure about this bit though, since we now have
> > per-task-per-cpu things, the profile_cpu is also used to !system_wide.
> 
> this actually means: if it is not system wide and not for an specific
> cpu, it must be for an specific pid.

But it can be for a specific pid and specific cpu.

> Not clear, right, you may want to profile an specific pid but only when
> it is running on an specific CPU... But at least this patch allows for
> specifiying either an specific CPU or an specific pid or systemwide.

Ah, right, not enough state to tell what we meant, fair enough.

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