linux-kernel - Re: perf tip: fails to convert comm

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Date:	Wed, 13 Nov 2013 19:29:53 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	David Ahern <dsahern@...il.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: perf tip: fails to convert comm

On Wed, Nov 13, 2013 at 03:07:46PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Nov 13, 2013 at 07:03:47PM +0100, Frederic Weisbecker escreveu:
> > On Tue, Nov 12, 2013 at 09:58:29PM -0700, David Ahern wrote:
> > > Hi Namhyung and Frederic:
> > > 
> > > If you recall I mentioned noting a problem with the callchain series
> > > showing comm's. Well, it fails on acme's perf/core. git bisect
> > > points to:
> > > 
> > > $ git bisect bad
> > > 4dfced359fbc719a35527416f1b4b3999647f68b is the first bad commit
> > > commit 4dfced359fbc719a35527416f1b4b3999647f68b
> > > Author: Namhyung Kim <namhyung.kim@....com>
> > > Date:   Fri Sep 13 16:28:57 2013 +0900
> > > 
> > >     perf tools: Get current comm instead of last one
> > > 
> > >     At insert time, a hist entry should reference comm at the time
> > > otherwise
> > >     it'll get the last comm anyway.
> > > 
> > > 
> > > How to re-create:
> > > 
> > > Start point is tools/perf directory for 3.12 (Linus tree):
> > >   $ perf sched record -o /tmp/perf.data -g -- make -j 16
> > >   $ perf script -i /tmp/perf.data > /tmp/1
> > > 
> > > cd to Arnaldo's tree, make perf and use it to create /tmp/2:
> > >   $ perf script -i /tmp/perf.data > /tmp/1
> > >   $ diff -U3 /tmp/1 /tmp/2 | less
> > > 
> > > You'll see a number of comm's showing as :<pid> instead of make, etc.
> > 
> > I see. I can reproduce, I'll check and see what happens. It would be nice if
> > we could have an option to dump internal perf events like comm events as well
> > in the perf script stream.
> 
> 'perf record -D' not enough?

No because it's not easy to correlate with perf script event output. Although it could
be if we simply dump the time the same way in both.
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