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Message-ID: <ZS2ecyCVpK8B2cQq@kernel.org>
Date: Mon, 16 Oct 2023 17:34:59 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v3] perf bench sched pipe: Add -G/--cgroups option
Em Mon, Oct 16, 2023 at 12:55:33PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Oct 16, 2023 at 12:51:52PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Now back at testing with with cgroups.
> Humm, even without the -G I get:
> [root@...e ~]# perf stat -e context-switches,cgroup-switches perf bench sched pipe -l 10000
> # Running 'sched/pipe' benchmark:
> # Executed 10000 pipe operations between two processes
> Total time: 0.082 [sec]
> 8.246400 usecs/op
> 121265 ops/sec
> Performance counter stats for 'perf bench sched pipe -l 10000':
> 20,002 context-switches
> 20,002 cgroup-switches
Same number, but then I forgot to add the 'taskset -c 0' part of the
command line, if I have it:
[root@...e ~]# perf stat -e context-switches,cgroup-switches taskset -c 0 perf bench sched pipe -l 10000
# Running 'sched/pipe' benchmark:
# Executed 10000 pipe operations between two processes
Total time: 0.072 [sec]
7.231500 usecs/op
138283 ops/sec
Performance counter stats for 'taskset -c 0 perf bench sched pipe -l 10000':
20,002 context-switches
3 cgroup-switches
0.082855113 seconds time elapsed
0.007765000 seconds user
0.074020000 seconds sys
[root@...e ~]# perf stat -e context-switches,cgroup-switches taskset -c 0 perf bench sched pipe -l 10000 -G AAA,BBB
# Running 'sched/pipe' benchmark:
# Executed 10000 pipe operations between two processes
Total time: 0.093 [sec]
9.341800 usecs/op
107045 ops/sec
Performance counter stats for 'taskset -c 0 perf bench sched pipe -l 10000 -G AAA,BBB':
20,004 context-switches
20,003 cgroup-switches
0.103436330 seconds time elapsed
0.018109000 seconds user
0.063058000 seconds sys
[root@...e ~]#
I.e. it works as in your results, but can you please spell out why that
'taskset -c 0' is needed to get these results?
I wasn't expecting the same number of cgroup-switches when not using
'taskset -c 0' :-\
- Arnaldo
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