linux-kernel - Re: [PATCH 17/54] gpu: drm: replace cpumask_weight with cpumask

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Date:   Tue, 25 Jan 2022 10:16:21 -0800
From:   Yury Norov <yury.norov@...il.com>
To:     Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        David Laight <David.Laight@...lab.com>,
        Joe Perches <joe@...ches.com>, Dennis Zhou <dennis@...nel.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Nicholas Piggin <npiggin@...il.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Alexey Klimov <aklimov@...hat.com>,
        linux-kernel@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 17/54] gpu: drm: replace cpumask_weight with cpumask_empty
 where appropriate

On Tue, Jan 25, 2022 at 1:28 AM Tvrtko Ursulin
<tvrtko.ursulin@...ux.intel.com> wrote:
>
>
> On 23/01/2022 18:38, Yury Norov wrote:
> > i915_pmu_cpu_online() calls cpumask_weight() to check if any bit of a
> > given cpumask is set. We can do it more efficiently with cpumask_empty()
> > because cpumask_empty() stops traversing the cpumask as soon as it finds
> > first set bit, while cpumask_weight() counts all bits unconditionally.
> >
> > Signed-off-by: Yury Norov <yury.norov@...il.com>
> > ---
> >   drivers/gpu/drm/i915/i915_pmu.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> > index ea655161793e..1894c876b31d 100644
> > --- a/drivers/gpu/drm/i915/i915_pmu.c
> > +++ b/drivers/gpu/drm/i915/i915_pmu.c
> > @@ -1048,7 +1048,7 @@ static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
> >       GEM_BUG_ON(!pmu->base.event_init);
> >
> >       /* Select the first online CPU as a designated reader. */
> > -     if (!cpumask_weight(&i915_pmu_cpumask))
> > +     if (cpumask_empty(&i915_pmu_cpumask))
> >               cpumask_set_cpu(cpu, &i915_pmu_cpumask);
> >
> >       return 0;
> >
>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
>
> I see it's a large series which only partially appeared on our mailing
> lists.

The series is here: https://lkml.org/lkml/2022/1/23/223
The branch: https://github.com/norov/linux/tree/bitmap-20220123

> So for instance it hasn't got tested by our automated CI. (Not
> that I expect any problems in this patch.)

Would be great if you give a test for the whole series, thanks!

> What are the plans in terms of which tree will it get merged through?

For the patches that will not be merged by maintainers of corresponding
subsystems, I'll use my bitmap branch and send it to linux-next.

Thanks,
Yury