From: Frederic Weisbecker <fweisbec@gmail.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Arun Sharma <asharma@fb.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
David Ahern <dsahern@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
Stephane Eranian <eranian@google.com>
Subject: Re: [RFC/PATCHSET 00/15] perf report: Add support to accumulate hist periods
Date: Fri, 28 Sep 2012 17:27:52 +0200 [thread overview]
Message-ID: <20120928152737.GB14215@somewhere.redhat.com> (raw)
In-Reply-To: <874nmivgqk.fsf@sejong.aot.lge.com>
On Fri, Sep 28, 2012 at 02:49:55PM +0900, Namhyung Kim wrote:
> Hi Frederic,
>
> On Fri, 28 Sep 2012 01:01:48 +0200, Frederic Weisbecker wrote:
> > When Arun was working on this, I asked him to explore if it could make sense to reuse
> > the "-b, --branch-stack" perf report option. Because after all, this feature is doing
> > about the same than "-b" except it's using callchains instead of full branch tracing.
> > But callchains are branches. Just a limited subset of all branches taken on excecution.
> > So you can probably reuse some interface and even ground code there.
> >
> > What do you think?
>
> Umm.. first of all, I'm not familiar with the branch stack thing. It's
> intel-specific, right?
>
> Also I don't understand what exactly you want here. What kind of
> interface did you say? Can you elaborate it bit more?
Look at commit b50311dc2ac1c04ad19163c2359910b25e16caf6
"perf report: Add support for taken branch sampling". It's doing almost
the same than you do, just using PERF_SAMPLE_BRANCH_STACK instead of
callchains.
> And AFAIK branch stack can collect much more branch information than
> just callstacks.
That's not a problem. Callchains are just a high-level filtered source of
branch samples. You don't need full branches to use "-b". Just use the flavour
of branch samples you want to make the sense you want on your branch sampling.
> Can we differentiate which is which easily?
Sure. If you have both sources in your perf.data (PERF_SAMPLE_BRANCH_STACK and
callchains), ask the user which one he wants. Otherwise defaults to what's there.
> Is there
> any limitation on using it? What if callstacks are not sync'ed with
> branch stacks - is it possible though?
It' better to make both sources mutually exclusive. Otherwise it's going
to be over-complicated.
>
> But I think it'd be good if the branch stack can be changed to call
> stack in general. Did you mean this?
That's a different. We might be able to post-process branch tracing and
build a callchain on top of it (following calls and ret). May be we will
one day. But they are different issues altogether.
Thanks.
next prev parent reply other threads:[~2012-09-28 15:27 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-13 7:19 Namhyung Kim
2012-09-13 7:19 ` [PATCH 01/15] perf hists: Add missing period_* fields when collapsing a hist entry Namhyung Kim
2012-09-13 7:19 ` [PATCH 02/15] perf hists: Introduce struct he_stat Namhyung Kim
2012-09-13 7:19 ` [PATCH 03/15] perf hists: Move he->stat.nr_events initialization to a template Namhyung Kim
2012-09-13 7:20 ` [PATCH 04/15] perf hists: Convert hist entry functions to use struct he_stat Namhyung Kim
2012-09-13 7:20 ` [PATCH 05/15] perf hists: Add more helpers for hist entry stat Namhyung Kim
2012-09-13 7:20 ` [PATCH 06/15] perf hists: Add support for accumulated stat of hist entry Namhyung Kim
2012-09-13 7:20 ` [PATCH 07/15] perf hists: Check if accumulated when adding a " Namhyung Kim
2012-09-13 7:20 ` [PATCH 08/15] perf callchain: Add a couple of callchain helpers Namhyung Kim
2012-09-13 7:20 ` [PATCH 09/15] perf hists: Let add_hist_entry to make a hist entry template Namhyung Kim
2012-09-13 7:20 ` [PATCH 10/15] perf hists: Accumulate hist entry stat based on the callchain Namhyung Kim
2012-09-13 7:20 ` [PATCH 11/15] perf hists: Sort hist entries by accumulated period Namhyung Kim
2012-09-13 7:20 ` [PATCH 12/15] perf ui/hist: Add support to accumulated hist stat Namhyung Kim
2012-09-13 7:20 ` [PATCH 13/15] perf ui/browser: " Namhyung Kim
2012-09-13 7:20 ` [PATCH 14/15] perf ui/gtk: " Namhyung Kim
2012-09-13 7:20 ` [PATCH 15/15] perf report: Add --cumulate option Namhyung Kim
2012-09-20 17:33 ` [RFC/PATCHSET 00/15] perf report: Add support to accumulate hist periods Arun Sharma
2012-09-25 4:57 ` Namhyung Kim
2012-09-27 23:01 ` Frederic Weisbecker
2012-09-28 5:49 ` Namhyung Kim
2012-09-28 7:07 ` Stephane Eranian
2012-09-28 15:14 ` Frederic Weisbecker
2012-09-28 16:36 ` Stephane Eranian
2012-09-28 15:27 ` Frederic Weisbecker [this message]
2012-10-29 19:08 ` Peter Zijlstra
2012-10-29 21:36 ` Arun Sharma
2012-10-30 6:59 ` Namhyung Kim
2012-10-30 8:17 ` Peter Zijlstra
2012-10-30 9:01 ` Ingo Molnar
2012-10-31 7:24 ` Namhyung Kim
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