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

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Message-ID: <e920081b-f590-7381-cf57-9f73fa846225@linux.intel.com>
Date:   Wed, 26 Jan 2022 09:43:50 +0000
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To:     Yury Norov <yury.norov@...il.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 25/01/2022 18:16, Yury Norov wrote:
> 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!

Can't really test the whole series for you, but if you want to send just 
the i915 patch standalone to the intel-gfx mailing list, that would 
trigger the CI run and if that passes we can merge that single one.

>> 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.

Or I guess we can wait for them to trickle back to us this way.

Regards,

Tvrtko