linux-kernel - RE: [PATCH V5 3/3] perf tool: check buildid for symoff

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Date:	Thu, 27 Nov 2014 14:09:51 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	"acme@...nel.org" <acme@...nel.org>,
	"jolsa@...hat.com" <jolsa@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: RE: [PATCH V5 3/3] perf tool: check buildid for symoff



> Hi Kan,
> 
> On Mon, 24 Nov 2014 11:00:29 -0500, Kan Liang wrote:
> > From: Kan Liang <kan.liang@...el.com>
> >
> > symoff can support both same binaries and different binaries. However,
> > the offset may be changed for different binaries. This patch checks
> > the buildid of perf.data. If they are from different binaries, print a
> > warning to notify the user.
> 
> Hmm.. I think that perf diff is supposed to compare performance between
> different (i.e. modified) binaries.  So there's a little point to print the
> warning IMHO - but I'm not insist it strongly..
> 
> Anyway, I think what we really need for the warning is different version of
> same binary.  For example, if data file 1 has DSO A and B, and data file 2 has
> DSO B and C, we should not consider they're different (unless build-ids of B
> in data file 1 and 2 are different) since A and C won't affect symoff
> comparision.
>

It looks good.
But I still slightly prefer to warn/inform the user if there are any different dsos,
not just from common part. But it's not a strong option.
I'd like to hear from others.

Arnaldo? Jirka?

Thanks,
Kan
 
> Thanks,
> Namhyung
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