linux-kernel - Re: [PATCH 2/3] perf bench futex-wake: Restore thread count default to online CPU count

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Date:   Thu, 05 Mar 2020 15:14:35 -0300
From:   Arnaldo Melo <arnaldo.melo@...il.com>
To:     Davidlohr Bueso <dave@...olabs.net>
CC:     Tommi Rantala <tommi.t.rantala@...ia.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Darren Hart <dvhart@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] perf bench futex-wake: Restore thread count default to online CPU count



On March 5, 2020 12:34:34 PM GMT-03:00, Davidlohr Bueso <dave@...olabs.net> wrote:
>On Thu, 05 Mar 2020, Arnaldo Carvalho de Melo wrote:
>
>>Em Thu, Mar 05, 2020 at 10:37:13AM +0200, Tommi Rantala escreveu:
>>> Since commit 3b2323c2c1c4 ("perf bench futex: Use cpumaps") the
>default
>>> number of threads the benchmark uses got changed from number of
>online
>>> CPUs to zero:
>>>
>>>   $ perf bench futex wake
>>>   # Running 'futex/wake' benchmark:
>>>   Run summary [PID 15930]: blocking on 0 threads (at [private] futex
>0x558b8ee4bfac), waking up 1 at a time.
>>>   [Run 1]: Wokeup 0 of 0 threads in 0.0000 ms
>>>   [...]
>>>   [Run 10]: Wokeup 0 of 0 threads in 0.0000 ms
>>>   Wokeup 0 of 0 threads in 0.0004 ms (+-40.82%)
>>>
>>> Restore the old behavior by grabbing the number of online CPUs via
>>> cpu->nr:
>>>
>>>   $ perf bench futex wake
>>>   # Running 'futex/wake' benchmark:
>>>   Run summary [PID 18356]: blocking on 8 threads (at [private] futex
>0xb3e62c), waking up 1 at a time.
>>>   [Run 1]: Wokeup 8 of 8 threads in 0.0260 ms
>>>   [...]
>>>   [Run 10]: Wokeup 8 of 8 threads in 0.0270 ms
>>>   Wokeup 8 of 8 threads in 0.0419 ms (+-24.35%)
>>>
>>> Fixes: 3b2323c2c1c4 ("perf bench futex: Use cpumaps")
>>
>>Thanks, tested and applied.
>
>Thanks!

Taking that as an Acked-by, ok?

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