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

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Date:   Tue, 25 Jan 2022 09:28:44 +0000
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To:     Yury Norov <yury.norov@...il.com>,
        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 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. So for instance it hasn't got tested by our automated CI. (Not 
that I expect any problems in this patch.)

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

Regards,

Tvrtko