linux-kernel - Re: [PATCH 1/2] perf report: ensure the perf DSO mapping matches what libdw sees

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Date:   Fri, 2 Jun 2017 16:49:10 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Milian Wolff <milian.wolff@...b.com>
Cc:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        Linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Namhyung Kim <namhyung@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 1/2] perf report: ensure the perf DSO mapping matches
 what libdw sees

Em Fri, Jun 02, 2017 at 06:21:44PM +0200, Milian Wolff escreveu:
> On Freitag, 2. Juni 2017 17:23:41 CEST Arnaldo Carvalho de Melo wrote:
> > Looks ok, having both implementations matching and the callchains making
> > sense for your workloads is a good way to verify the sanity, thanks.

> > I wonder if we shouldn't somehow script this, i.e. build it with one
> > implementation, generate output from some test workload, build it with
> > the other, second output, diff it, report when not the same.
 
> That does sound like a good idea, but I'm unsure how to do it. Note that many 
> "simple" tests work just fine. Only larger complicated workloads trigger this 
> issue for me.
 
> One potential way to test it would be `perf archive` - i.e. I send you the 
> binaries involved and then we can use perf script diffing to ensure it all 
> works...

Humm, I'm trying to cook up a:

  perf data filter --pid 12345 --perf-data-offset 1234567 --output perf.data.subset

to allow when finding some case like that to get a small subset of a
perf.data file with just the sample we want to get the backtrace from +
the mmaps, etc up to that point.

With that I could keep a repo of interesting perf.data files to have in
my regression tests.

- Arnaldo