linux-kernel - Re: Optimize perf stat for large number of events/cpus

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Date:   Wed, 27 Nov 2019 21:01:30 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Andi Kleen <ak@...ux.intel.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
CC:     Andi Kleen <andi@...stfloor.org>, jolsa@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Optimize perf stat for large number of events/cpus

On November 27, 2019 8:26:57 PM GMT-03:00, Andi Kleen <ak@...ux.intel.com> wrote:
>On Wed, Nov 27, 2019 at 12:43:05PM -0300, Arnaldo Carvalho de Melo
>wrote:
>> So, have you tried running 'perf test' after each cset is applied and
>> built?
>
>I ran it at the end, but there are quite a few fails out of the box,
>so I missed that one thanks.
>
>This patch fixes it. Let me know if I should submit it in a more
>formal way.
>
>---
>
>Fix event times test case
>
>Reported-by: Arnaldo
>Signed-off-by: Andi Kleen <ak@...ux.intel.com>
>
>diff --git a/tools/perf/lib/evsel.c b/tools/perf/lib/evsel.c
>index 4c6485fc31b9..4dc06289f4c7 100644
>--- a/tools/perf/lib/evsel.c
>+++ b/tools/perf/lib/evsel.c
>@@ -224,7 +224,7 @@ int perf_evsel__enable(struct perf_evsel *evsel)
> 	int i;
> 	int err = 0;
> 
>-	for (i = 0; i < evsel->cpus->nr && !err; i++)
>+	for (i = 0; i < xyarray__max_x(evsel->fd) && !err; i++)
> 		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_ENABLE, NULL, i);
> 	return err;
> }
>@@ -239,7 +239,7 @@ int perf_evsel__disable(struct perf_evsel *evsel)
> 	int i;
> 	int err = 0;
> 
>-	for (i = 0; i < evsel->cpus->nr && !err; i++)
>+	for (i = 0; i < xyarray__max_x(evsel->fd) && !err; i++)
> 		err = perf_evsel__run_ioctl(evsel, PERF_EVENT_IOC_DISABLE, NULL, i);
> 	return err;
> }
>diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
>index 59b9b4f3fe34..0844e3e29fb0 100644
>--- a/tools/perf/util/evsel.c
>+++ b/tools/perf/util/evsel.c
>@@ -1853,6 +1853,10 @@ int perf_evsel__open_per_cpu(struct evsel
>*evsel,
> 			     struct perf_cpu_map *cpus,
> 			     int cpu)
> {
>+	if (cpu == -1)
>+		return evsel__open_cpu(evsel, cpus, NULL, 0,
>+					cpus ? cpus->nr : 1);
>+
> 	return evsel__open_cpu(evsel, cpus, NULL, cpu, cpu + 1);
> }
> 

Just save me some time by saying to which cset in v8 I should squash this into, so that we keep the whole shebang bisectable,

Thanks,

- Arnaldo