From 0d3d237651fd7a01fe5dc501b0d170a43d8156ba Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Mon, 17 Jan 2022 13:09:31 -0300
Subject: [PATCH] perf evlist: No need to setup affinities when disabling
events for pid targets
When the target is a pid, not started by 'perf stat' we need to disable
the events, and in that case there is no need to setup affinities as we
use a dummy CPU map, with just one entry set to -1.
So stop doing it to avoid this needless call to sched_getaffinity():
# strace -ke sched_getaffinity perf stat -e cycles -p 241957 sleep 1
<SNIP>
sched_getaffinity(0, 512, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]) = 8
> /usr/lib64/libc-2.33.so(sched_getaffinity@@GLIBC_2.3.4+0x1a) [0xe6eea]
> /var/home/acme/bin/perf(affinity__setup+0x6a) [0x532a2a]
> /var/home/acme/bin/perf(__evlist__disable.constprop.0+0x27) [0x4b9827]
> /var/home/acme/bin/perf(cmd_stat+0x29b5) [0x431725]
> /var/home/acme/bin/perf(run_builtin+0x6a) [0x4a2cfa]
> /var/home/acme/bin/perf(main+0x612) [0x40f8c2]
> /usr/lib64/libc-2.33.so(__libc_start_main+0xd4) [0x27b74]
> /var/home/acme/bin/perf(_start+0x2d) [0x40fadd]
<SNIP>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220117160931.1191712-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evlist.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index ae6d4363da76e..eaad04e1672a4 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -430,15 +430,19 @@ static void __evlist__disable(struct evlist *evlist, char *evsel_name)
{
struct evsel *pos;
struct evlist_cpu_iterator evlist_cpu_itr;
- struct affinity affinity;
+ struct affinity saved_affinity, *affinity = NULL;
bool has_imm = false;
- if (affinity__setup(&affinity) < 0)
- return;
+ // See explanation in evlist__close()
+ if (!cpu_map__is_dummy(evlist->core.cpus)) {
+ if (affinity__setup(&saved_affinity) < 0)
+ return;
+ affinity = &saved_affinity;
+ }
/* Disable 'immediate' events last */
for (int imm = 0; imm <= 1; imm++) {
- evlist__for_each_cpu(evlist_cpu_itr, evlist, &affinity) {
+ evlist__for_each_cpu(evlist_cpu_itr, evlist, affinity) {
pos = evlist_cpu_itr.evsel;
if (evsel__strcmp(pos, evsel_name))
continue;
@@ -454,7 +458,7 @@ static void __evlist__disable(struct evlist *evlist, char *evsel_name)
break;
}
- affinity__cleanup(&affinity);
+ affinity__cleanup(affinity);
evlist__for_each_entry(evlist, pos) {
if (evsel__strcmp(pos, evsel_name))
continue;
--
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