linux-kernel - RE: [PATCH 2/2] perf,tools: check and re-organize evsel cpu maps

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Date:	Tue, 30 Jun 2015 13:42:49 +0000
From:	"Liang, Kan" <kan.liang@...el.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	"acme@...nel.org" <acme@...nel.org>,
	"jolsa@...nel.org" <jolsa@...nel.org>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>,
	"eranian@...gle.com" <eranian@...gle.com>,
	"Hunter, Adrian" <adrian.hunter@...el.com>,
	"dsahern@...il.com" <dsahern@...il.com>,
	"a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/2] perf,tools: check and re-organize evsel cpu maps



> > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index
> > 6cfdee6..f179379 100644
> > --- a/tools/perf/util/evlist.c
> > +++ b/tools/perf/util/evlist.c
> > @@ -1101,6 +1101,71 @@ int perf_evlist__mmap(struct perf_evlist
> *evlist, unsigned int pages,
> >  	return perf_evlist__mmap_ex(evlist, pages, overwrite, 0, false);  }
> >
> > +static int cmp_ids(const void *a, const void *b) {
> > +	return *(int *)a - *(int *)b;
> > +}
> > +
> > +static int perf_evlist__check_evsel_cpus(struct perf_evlist *evlist,
> > +struct perf_evsel *evsel) {
> > +	const struct cpu_map *cpus = evlist->cpus;
> > +	const int ncpus = cpu_map__nr(evlist->cpus);
> > +	int j = 0, cpu_nr = 0, tmp = 0;
> > +	int i;
> > +
> > +	/* ensure we process id in increasing order */
> > +	qsort(evlist->cpus->map, evlist->cpus->nr, sizeof(int), cmp_ids);
> 
> wouldn't sorting maps affect some other code?
> 

I didn't find any bad effect after sorting the maps.
Any codes I need to check?

> > +
> > +	/* find the common cpus between evsel and evlist. */
> > +	for (i = 0; i < cpu_map__nr(evsel->cpus);)  {
> > +
> > +		if (j >= ncpus) {
> > +			evsel->cpus->map[i++] = -1;
> > +			continue;
> > +		}
> > +		for (; j < ncpus; j++) {
> > +			if (cpus->map[j] < evsel->cpus->map[i])
> > +				continue;
> > +			if (cpus->map[j] == evsel->cpus->map[i]) {
> > +				cpu_nr++;
> > +				j++;
> 
> hum, do you skip 1 item in cpus by j++ here and in for loop header?
> 
 
If matching, it will break the j loop then. There is no chance to
j++ in the loop header. So I do j++ here, and it will not skip any items.

> also some easy it'd be easier to read if you identify different cpu maps
> somehow.. like evlist_cpus and evsel_cpus or such
>
OK. I will change the name.
 
> I have no way of testing this.. could you please add automated test for this
> one?

OK

Thanks,
Kan
> 
> thanks,
> jirka
> 
> > +				i++;
> > +			} else
> > +				evsel->cpus->map[i++] = -1;
> > +			break;
> > +		}
> > +	}
> > +
> 
> SNIP
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