linux-kernel - Re: [PATCH] perf: Fallback to MAP_

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Message-ID: <20140821154828.GN2892@kernel.org>
Date:	Thu, 21 Aug 2014 12:48:28 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Don Zickus <dzickus@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, eranian@...gle.com,
	jmario@...hat.com
Subject: Re: [PATCH] perf: Fallback to MAP__FUNCTION if daddr maps are NULL

Em Thu, Aug 21, 2014 at 09:04:51AM +0200, Jiri Olsa escreveu:
> On Wed, Aug 20, 2014 at 11:25:11PM -0400, Don Zickus wrote:
> > As we run "perf c2c" on more applications, we noticed we're missing significant
> > samples from a common customer's application.  Looking at the
> > /proc/<pid>/maps file for the app, we see "rwxs" and "rwxp" permissions on many
> > of the shared memory & heap regions, and on all the thread stacks.
> > 
> > Because those regions have the "x" bit set, perf marks them with a MAP_FUNCTION
> > type.  Hence ip_resolve_data() never finds load or store events coming from
> > them.
> > 
> > We fixed this by re-calling thread__find_addr_location with MAP__FUNCTION in
> > the case where map is NULL as a last ditch effort to map the sample before
> > giving up and dropping it.
> > 
> > Reported-by: Joe Mario <jmario@...hat.com>
> > Tested-by: Joe Mario <jmario@...hat.com>
> > Signed-off-by: Don Zickus <dzickus@...hat.com>
> 
> Acked-by: Jiri Olsa <jolsa@...nel.org>

Thanks, applied.

- Arnaldo
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