linux-kernel - Re: [GIT PULL 00/21] perf/core improvements and fixes

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Date:	Tue, 13 Nov 2012 10:20:30 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, Ingo Molnar <mingo@...nel.org>,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Irina Tirdea <irina.tirdea@...il.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>, stable@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Vinson Lee <vlee@...tter.com>,
	Zheng Liu <wenqing.lz@...bao.com>
Subject: Re: [GIT PULL 00/21] perf/core improvements and fixes

On Mon, 12 Nov 2012 13:01:39 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 12, 2012 at 02:55:46PM +0100, Jiri Olsa escreveu:
>> On Mon, Nov 12, 2012 at 11:10:52AM +0900, Namhyung Kim wrote:
>> > On Fri,  9 Nov 2012 18:42:49 -0300, Arnaldo Carvalho de Melo wrote:
>> > > . Add a 'link' method for hists, so that we can have the leader with
>> > >   buckets for all the entries in all the hists.  This new method
>> > >   is now used in the default 'diff' output, making the sum of the 'baseline'
>> > >   column be 100%, eliminating blind spots. Now we need to use this
>> > >   for 'diff' with > 2 perf.data files and for multi event 'report' and
>> > >   'annotate'.
>
>> > I'm not sure it can be used for group report at least in its current
>> > form.  IIUC it connects multiple hist entries using a list head and
>> > create a dummy entry in the leader if need be.  But it didn't handle
>> > non-leader entries so it's hard to tell which is which if less entries
>> > are present only.  For example consider following case:
>
>> > 	leader		member1		member2
>> > 	A		A		A
>> > 	B
>> > 			C
>> > 					D
>
>> > where leader, member1 and member2 are evsel/hists and A, B, C and D are
>> > hist entries.  After 'linking' the entries the leader will have
>> > following linkage:
>
>> > 	leader
>> > 	A	->	A	->	A
>> > 	B
>> > 	C (dummy) ->	C
>> > 	D (dummy)		->	D
>
>> > In this case, for entry A the leader can determine which entry came from
>> > which hists by looking its order in the list.  For entry B the leader
>> > can use zero value for them since the list is empty.  However for
>> > entries C and D, it cannot know which one is the right hists unless it
>> > records a hist index or creates dummy entry and insert it in a correct
>> > order (looks far from an optimal solution).  Am I missing something?
>
>> there's hists pointer in hist_entry if that's what you look for
>
> And from there to evsel->idx. In your patchset you even introduce
> hists_2_evsel(), right?

Ah, okay.  I worried about a possiblity of non-consecutive event groups
for some reason, but that's not gonna happen in the future?

Thanks,
Namhyung
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