linux-kernel - Re: [PATCH 23/24] perf buildid-list: Add support for mmap2's buildid events

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Message-ID: <20201117205037.GI1216482@krava>
Date:   Tue, 17 Nov 2020 21:50:37 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, lkml <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Michael Petlan <mpetlan@...hat.com>,
        Song Liu <songliubraving@...com>,
        Ian Rogers <irogers@...gle.com>,
        Stephane Eranian <eranian@...gle.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH 23/24] perf buildid-list: Add support for mmap2's buildid
 events

On Tue, Nov 17, 2020 at 02:54:00PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Tue, Nov 17, 2020 at 04:21:40PM +0100, Jiri Olsa escreveu:
> > On Tue, Nov 17, 2020 at 09:50:40AM -0300, Arnaldo Carvalho de Melo wrote:
> > > Em Tue, Nov 17, 2020 at 12:00:52PM +0100, Jiri Olsa escreveu:
> > > > Add buildid-list support for mmap2's build id data, so we can
> > > > display build ids for dso objects for data without the build
> > > > id cache update.
> > > 
> > > >   $ perf buildid-list
> > > >   1805c738c8f3ec0f47b7ea09080c28f34d18a82b /usr/lib64/ld-2.31.so
> > > >   d278249792061c6b74d1693ca59513be1def13f2 /usr/lib64/libc-2.31.so
> > > > 
> > > > By default only dso objects with hits are shown.
> > > 
> > > Would be interesting to be able to show all the build ids that are
> > > there. a 'perf buildid-list --all' or make this under --force?
> > 
> > ok, will check.. one other tool I think would be handy is
> > to show which debuginfo is not available, because it can
> > change the report a lot - missing symbols are not getting
> > accounted, and their hits are accounted only as separated
> > addresses
> 
> Right, as below.
> 
> So you suggest something like:
> 
>   # perf buildid-cache --fetch-missing-debuginfo

haven't thought about interface yet, just noticed it's something
that's not so easy to find out while we can present it to user quite
easily

the interface needs to have perf.data in it, because buildid-cache
does not work on top of perf.data, perhaps something like:

   # perf report --show-missing-debuginfo

or on top of current interface:

   # perf buildid-cache -a perf.data --show-missing-debuginfo

jirka