linux-kernel - RE: [PATCH 43/54] drivers/hv: replace cpumask_weight with cpumask_weight

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Date:   Sun, 23 Jan 2022 22:02:09 +0000
From:   Haiyang Zhang <haiyangz@...rosoft.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" <linux-kernel@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>
Subject: RE: [PATCH 43/54] drivers/hv: replace cpumask_weight with
 cpumask_weight_eq



> -----Original Message-----
> From: Yury Norov <yury.norov@...il.com>
> Sent: Sunday, January 23, 2022 1:39 PM
> 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; KY Srinivasan
> <kys@...rosoft.com>; Haiyang Zhang <haiyangz@...rosoft.com>; Stephen Hemminger
> <sthemmin@...rosoft.com>; Wei Liu <wei.liu@...nel.org>; Dexuan Cui <decui@...rosoft.com>;
> linux-hyperv@...r.kernel.org
> Subject: [PATCH 43/54] drivers/hv: replace cpumask_weight with cpumask_weight_eq
> 
> init_vp_index() calls cpumask_weight() to compare the weights of cpumasks
> We can do it more efficiently with cpumask_weight_eq because conditional
> cpumask_weight may stop traversing the cpumask earlier (at least one), as
> soon as condition is met.
> 
> Signed-off-by: Yury Norov <yury.norov@...il.com>
> ---
>  drivers/hv/channel_mgmt.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index 60375879612f..7420a5fd47b5 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -762,8 +762,8 @@ static void init_vp_index(struct vmbus_channel *channel)
>  		}
>  		alloced_mask = &hv_context.hv_numa_map[numa_node];
> 
> -		if (cpumask_weight(alloced_mask) ==
> -		    cpumask_weight(cpumask_of_node(numa_node))) {
> +		if (cpumask_weight_eq(alloced_mask,
> +			    cpumask_weight(cpumask_of_node(numa_node)))) {
>  			/*
>  			 * We have cycled through all the CPUs in the node;
>  			 * reset the alloced map.

Thanks.

Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>