RE: [PATCH 43/54] drivers/hv: replace cpumask_weight with cpumask_weight_eq

[Haiyang Zhang]

> -----Original Message-----
> From: Yury Norov <yury.norov@xxxxxxxxx>
> Sent: Sunday, January 23, 2022 1:39 PM
> To: Yury Norov <yury.norov@xxxxxxxxx>; Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>;
> Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>; Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>;
> Michał Mirosław <mirq-linux@xxxxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>;
> Peter Zijlstra <peterz@xxxxxxxxxxxxx>; David Laight <David.Laight@xxxxxxxxxx>; Joe Perches
> <joe@xxxxxxxxxxx>; Dennis Zhou <dennis@xxxxxxxxxx>; Emil Renner Berthing <kernel@xxxxxxxx>;
> Nicholas Piggin <npiggin@xxxxxxxxx>; Matti Vaittinen <matti.vaittinen@xxxxxxxxxxxxxxxxx>;
> Alexey Klimov <aklimov@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; KY Srinivasan
> <kys@xxxxxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Stephen Hemminger
> <sthemmin@xxxxxxxxxxxxx>; Wei Liu <wei.liu@xxxxxxxxxx>; Dexuan Cui <decui@xxxxxxxxxxxxx>;
> linux-hyperv@xxxxxxxxxxxxxxx
> 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@xxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxx>