On Fri 15-09-17 17:23:25, Kemi Wang wrote:
[...]
> @@ -2743,6 +2745,17 @@ static inline void zone_statistics(struct zone 
> *preferred_zone, struct zone *z)
>  #ifdef CONFIG_NUMA
>       enum numa_stat_item local_stat = NUMA_LOCAL;
>  
> +     /*
> +      * skip zone_statistics() if vmstat is a coarse mode or zone statistics
> +      * is inactive in auto vmstat mode
> +      */
> +
> +     if (vmstat_mode) {
> +             if (vmstat_mode == VMSTAT_COARSE_MODE)
> +                     return;
> +     } else if (disable_zone_statistics)
> +             return;
> +
>       if (z->node != numa_node_id())
>               local_stat = NUMA_OTHER;

A jump label could make this completely out of the way for the case
where every single cycle matters.
-- 
Michal Hocko
SUSE Labs

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