linux-kernel - Re: [PATCH -tip v3 3/6] perf branch trace: print pid and command

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Date:	Wed, 6 Apr 2011 16:55:23 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	David Ahern <dsahern@...il.com>,
	Akihiro Nagai <akihiro.nagai.hw@...achi.com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	2nddept-manager@....hitachi.co.jp,
	Paul Mackerras <paulus@...ba.org>, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH -tip v3 3/6] perf branch trace: print pid and command

On Wed, Apr 06, 2011 at 11:09:58AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Apr 06, 2011 at 02:15:07PM +0200, Frederic Weisbecker escreveu:
> > On Fri, Apr 01, 2011 at 11:11:10AM -0600, David Ahern wrote:
> > > On 04/01/11 09:13, Frederic Weisbecker wrote:
> > > > But well, we can start simple and make and just do the => trick
> > > > if we have PERF_SAMPLE_ADDR and resolve addr if the user asked
> > > > the sym. Then when we have the graph output, have these per evsel
> > > > display callbacks.
> 
> > > There is another email thread about page faults. The user wants sample
> > > address resolved to symbols. I was going to look into it next week when
> > > I get back from vacation.
>  
> > What we seem to need for that is to bring a pagefault tracepoint. We had
> > propositions for that in the past, but work on this is in pause mode it
> > seems.
> 
> Isn't there one in the 'tip/tmp.perf/trace' tmp branch? Lemme see...
> 
> Yeah, and it is even yours ;-)
> 
> commit 6a824e89c0dfe6bce3d7e85f987ec9c8e7304b34
> Author: Frederic Weisbecker <fweisbec@...il.com>
> Date:   Fri Nov 12 05:35:06 2010 +0100
> 
>     perf, mm: Add fault tracing
>     
>     Part of that are two modified patches from Jiri Olsa who added the
>     fault tracepoints. I had to split them in two tracepoints so that we get
>     the faults handling duration.
>     
>     Originally-from: Frederic Weisbecker <fweisbec@...il.com>
>     Signed-off-by: Ingo Molnar <mingo@...e.hu>
>     Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

That forgets to mention it's based on Jiri Olsa's patch :)

"tracing,mm - add kernel pagefault tracepoint for x86 & x86_64"

(Message id <1289466549-7602-3-git-send-email-jolsa@...hat.com>).

> 
> Can we dust this one off and get the ball rolling again? 

I prefer someone comes with a real need before me or Jiri respin
that. There was perf trace but its development seems to be stale
now.

The page fault software event seem to be enough for basic
dump requests. I don't like software events and prefer tracepoints
in general but as long as the current implementation is enough
and people don't need to measure page fault servicing time,
write scripts or so, we are probably fine.
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