linux-kernel - Re: [PATCH/RFC 09/16] perf tools: Update hist entry's hists pointer

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Date:	Mon, 14 Dec 2015 10:51:04 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [PATCH/RFC 09/16] perf tools: Update hist entry's hists pointer

On Mon, Dec 14, 2015 at 12:28:12AM +0100, Jiri Olsa wrote:
> On Mon, Dec 14, 2015 at 12:23:30AM +0100, Jiri Olsa wrote:
> > On Thu, Dec 10, 2015 at 04:53:28PM +0900, Namhyung Kim wrote:
> > > When sample is processed using multi-thread, each sample is gathered on
> > > each thread's hist tree and then merged into the real hist tree.  But
> > > hist_entry->hists pointer was not updated so it could refer wrong hists
> > > resulted in missing outputs.
> > > 
> > > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > > ---
> > >  tools/perf/util/hist.c | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > > 
> > > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> > > index ea4f3ad978b0..a12e5022fe04 100644
> > > --- a/tools/perf/util/hist.c
> > > +++ b/tools/perf/util/hist.c
> > > @@ -1008,6 +1008,14 @@ bool hists__collapse_insert_entry(struct hists *hists __maybe_unused,
> > 
> > there's 'struct hists *hists __maybe_unused' in hists__collapse_insert_entry def..

OK, will remove.

> 
> also hists__collapse_insert_entry is global which seems unnecessary

What do you mean?  The hists__collapse_insert_entry() will be used by
collect_worker thread.

Thanks,
Namhyung


> 
> jirka
> 
> > 
> > jirka
> > 
> > >  	}
> > >  	hists->nr_entries++;
> > >  
> > > +	/*
> > > +	 * If a hist entry is processed in multi-threaded environment,
> > > +	 * it points to a dummy local hists which was used only for
> > > +	 * intermidate processing.  So update it to a real one so that
> > > +	 * it can find the correct info later.
> > > +	 */
> > > +	he->hists = hists;
> > > +
> > >  	rb_link_node(&he->rb_node_in, parent, p);
> > >  	rb_insert_color(&he->rb_node_in, root);
> > >  	return true;
> > > -- 
> > > 2.6.2
> > > 
--
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