linux-kernel - Re: [PATCH 1/1] perf,tools: open event on evsel cpus and threads

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Message-ID: <20150831213434.GL4423@kernel.org>
Date:	Mon, 31 Aug 2015 18:34:34 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	"Liang, Kan" <kan.liang@...el.com>
Cc:	Jiri Olsa <jolsa@...hat.com>,
	"jolsa@...nel.org" <jolsa@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] perf,tools: open event on evsel cpus and threads

Em Mon, Aug 31, 2015 at 09:28:43PM +0000, Liang, Kan escreveu:
> 
> 
> 
> > 
> > Em Mon, Aug 31, 2015 at 09:06:29PM +0000, Liang, Kan escreveu:
> > >
> > >
> > > > Em Fri, Aug 21, 2015 at 03:54:36PM +0200, Jiri Olsa escreveu:
> > > > > On Fri, Aug 21, 2015 at 02:23:14AM -0400, kan.liang@...el.com wrote:
> > > > > > From: Kan Liang <kan.liang@...el.com>
> > > > > >
> > > > > > evsel may have different cpus and threads as evlist's.
> > > > > > Use it's own cpus and threads, when open evsel in perf record.
> > > > >
> > > > > Acked-by: Jiri Olsa <jolsa@...nel.org>
> > > >
> > > > Applying, I wonder if this isn't affecting other tools as well...
> > > > And also
> > >
> > > No, it doesn't affect other tools.
> > >
> > > > perf_evlist__open(), that has to be fixed as well, right?
> > > >
> > >
> > > Umm... Right.
> > > We should fix it in perf_evlist__open as well.
> > > IIRC, Jirka once planned to send out a cleanup patch separately for
> > > this kind of issue (perf_evsel__enable also need to be fixed) on other
> > > tools.
> > 
> > So now that we have a backpointer, perhaps we should have a:
> > 
> > struct thread_map *perf_evsel__threads(struct perf_evsel *evsel) {
> > 	return evsel->threads ?: evsel->evlist ? evsel->evlist->threads :
> > NULL; }
> > 
> > Ditto for cpus and then change all occurrences of evsel->threads with
> > perf_evsel__threads(), right?
> 
> No. We need to change all evlist->threads with evsel->threads.
> Ditto for cpus.
> The event should use its own thread/cpu list.

Which is equivalent, but IIRC doing it the way you do is better because
we do that forwarding already, right?

Lemme check... Yeah, it is done in perf_evlist__propagate_maps(), so, as
long as that function was called, we can access evsel->{threads,cpus}
and it will use evlist->{threads,cpus} if those entries were not set
before perf_evlist__propagate_maps() was called.

- Arnaldo
 
> > > Thanks,
> > > Kan
> > >
> > > > - Arnaldo
> > > >
> > > > > thanks,
> > > > > jirka
> > > > >
> > > > > >
> > > > > > Signed-off-by: Kan Liang <kan.liang@...el.com>
> > > > > > ---
> > > > > >  tools/perf/builtin-record.c | 2 +-
> > > > > >  tools/perf/util/evlist.c    | 4 ++++
> > > > > >  2 files changed, 5 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/tools/perf/builtin-record.c
> > > > > > b/tools/perf/builtin-record.c index 25cf6b4..a0178bf 100644
> > > > > > --- a/tools/perf/builtin-record.c
> > > > > > +++ b/tools/perf/builtin-record.c
> > > > > > @@ -279,7 +279,7 @@ static int record__open(struct record *rec)
> > > > > >
> > > > > >  	evlist__for_each(evlist, pos) {
> > > > > >  try_again:
> > > > > > -		if (perf_evsel__open(pos, evlist->cpus, evlist-
> > >threads) <
> > > > 0) {
> > > > > > +		if (perf_evsel__open(pos, pos->cpus, pos-
> > >threads) < 0) {
> > > > > >  			if (perf_evsel__fallback(pos, errno, msg,
> > > > sizeof(msg))) {
> > > > > >  				if (verbose)
> > > > > >  					ui__warning("%s\n", msg);
> > > > > > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> > > > > > index 373f65b..be6fde9 100644
> > > > > > --- a/tools/perf/util/evlist.c
> > > > > > +++ b/tools/perf/util/evlist.c
> > > > > > @@ -1179,6 +1179,10 @@ int perf_evlist__apply_filters(struct
> > > > perf_evlist *evlist, struct perf_evsel **e
> > > > > >  		if (evsel->filter == NULL)
> > > > > >  			continue;
> > > > > >
> > > > > > +		/*
> > > > > > +		 * filters only work for tracepoint event, which
> > doesn't
> > > > have cpu limit.
> > > > > > +		 * So evlist and evsel should always be same.
> > > > > > +		 */
> > > > > >  		err = perf_evsel__apply_filter(evsel, ncpus,
> > nthreads,
> > > > evsel->filter);
> > > > > >  		if (err) {
> > > > > >  			*err_evsel = evsel;
> > > > > > --
> > > > > > 1.8.3.1
> > > > > >
--
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