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Date:   Tue, 3 Jul 2018 13:54:06 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Kirill Tkhai <ktkhai@virtuozzo.com>
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Subject: Re: [PATCH v8 13/17] mm: Set bit in memcg shrinker bitmap on first
 list_lru item apearance
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On Tue, 03 Jul 2018 18:10:56 +0300 Kirill Tkhai <ktkhai@virtuozzo.com> wrote:

> Introduce set_shrinker_bit() function to set shrinker-related
> bit in memcg shrinker bitmap, and set the bit after the first
> item is added and in case of reparenting destroyed memcg's items.
> 
> This will allow next patch to make shrinkers be called only,
> in case of they have charged objects at the moment, and
> to improve shrink_slab() performance.
> 
> ...
>
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1308,6 +1308,18 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
>  
>  extern int memcg_expand_shrinker_maps(int new_id);
>  
> +static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
> +					  int nid, int shrinker_id)
> +{
> +	if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
> +		struct memcg_shrinker_map *map;
> +
> +		rcu_read_lock();
> +		map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
> +		set_bit(shrinker_id, map->map);
> +		rcu_read_unlock();
> +	}
> +}

Three callsites, this seem rather large for inlining.