linux-kernel - Re: [PATCH 2/7] perf tools: Account entry stats when it's added to the output tree

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Date:	Wed, 23 Apr 2014 23:43:16 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH 2/7] perf tools: Account entry stats when it's added to
 the output tree

Hi Jiri,

2014-04-23 (수), 15:35 +0200, Jiri Olsa:
> On Wed, Apr 23, 2014 at 04:00:03PM +0900, Namhyung Kim wrote:
> > Currently, accounting each sample is done in multiple places - once
> > when adding them to the input tree, other when adding them to the
> > output tree.  It's not only confusing but also can cause a subtle
> > problem since concurrent processing like in perf top might see the
> > updated stats before adding entries into the output tree - like seeing
> > more (blank) lines at the end and/or slight inaccurate percentage.
> > 
> > To fix this, only account the entries when it's moved into the output
> > tree so that they cannot be seen prematurely.  There're some
> > exceptional cases here and there - they should be addressed separately
> > with comments.
> 
> sry to be PITA, but need to ask you to split the patch,
> otherwise I'd get beaten for that ;-)

No problem.  I'll split it in the next spin.

> 
> I can see several separated changes here:
>  * remove stats for input tree (as stated in changelog)
>  * hists__inc_nr_entries -> hists__inc_stats rename
>  * add hists__reset_stats function
>  * move hists__calc_col_len out of hists__inc_nr_entries
> 
> 
> > 
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> 
> SNIP
> 
> >  
> > diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
> > index aed52036468d..4bdcc040b216 100644
> > --- a/tools/perf/builtin-report.c
> > +++ b/tools/perf/builtin-report.c
> > @@ -85,6 +85,10 @@ static void report__inc_stats(struct report *rep, struct hist_entry *he)
> >  	 */
> >  	if (he->stat.nr_events == 1)
> >  		rep->nr_entries++;
> > +
> > +	hists__inc_nr_events(he->hists, PERF_RECORD_SAMPLE);
> > +	if (!he->filtered)
> > +		he->hists->stats.nr_non_filtered_samples++;
> 
> could you put here some comments as for the diff command
> I mean why is this exception in stats counting for input tree

Will do as well.

Thanks,
Namhyung



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