linux-kernel - Re: [PATCH v7 09/12] perf stat: Use affinity for opening events

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Date:   Wed, 20 Nov 2019 14:31:01 -0800
From:   Andi Kleen <ak@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Andi Kleen <andi@...stfloor.org>, acme@...nel.org,
        jolsa@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 09/12] perf stat: Use affinity for opening events

> > +		evlist__for_each_cpu (evsel_list, i, cpu) {
> > +			affinity__set(&affinity, cpu);
> > +			/* First close errored or weak retry */
> > +			evlist__for_each_entry(evsel_list, counter) {
> > +				if (!counter->reset_group && !counter->errored)
> > +					continue;
> > +				if (evsel__cpu_iter_skip_no_inc(counter, cpu))
> > +					continue;
> > +				perf_evsel__close_cpu(&counter->core, counter->cpu_iter);
> > +			}
> > +			/* Now reopen weak */
> > +			evlist__for_each_entry(evsel_list, counter) {
> > +				if (!counter->reset_group && !counter->errored)
> > +					continue;
> > +				if (evsel__cpu_iter_skip(counter, cpu))
> > +					continue;
> 
> why staring at this I wonder why can't we call perf_evsel__close_cpu in
> here and remove the above loop? together with evsel__cpu_iter_skip_no_inc
> function

We only want to close events which errored or need a weak entry.
The others can stay open.  perf_evsel__close_cpu closes all unconditionally.

-Andi