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

[Davidlohr Bueso]

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!