Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory uncharging

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory uncharging
Date	2017-08-30 14:40 +0200
Message-ID	<ukarM-8kx-5@gated-at.bofh.it> (permalink)
References	<ujUn0-6IJ-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue 29-08-17 11:01:50, Roman Gushchin wrote:
[...]
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b9cf3cf4a3d0..a69d23082abf 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1792,6 +1792,9 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
>  	}
>  	stock->nr_pages += nr_pages;
>  
> +	if (stock->nr_pages > CHARGE_BATCH)
> +		drain_stock(stock);
> +
>  	local_irq_restore(flags);
>  }

Why do we need this? In other words, why cannot we rely on draining we
already do?

>  
> @@ -5886,8 +5889,7 @@ void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
>  
>  	this_cpu_sub(memcg->stat->count[MEMCG_SOCK], nr_pages);
>  
> -	page_counter_uncharge(&memcg->memory, nr_pages);
> -	css_put_many(&memcg->css, nr_pages);
> +	refill_stock(memcg, nr_pages);
>  }

This makes sense to me.
-- 
Michal Hocko
SUSE Labs

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Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory  uncharging Michal Hocko <mhocko@kernel.org> - 2017-08-30 14:40 +0200
  Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory  uncharging Michal Hocko <mhocko@kernel.org> - 2017-08-30 15:00 +0200
    Re: [PATCH] mm: memcontrol: use per-cpu stocks for socket memory  uncharging Michal Hocko <mhocko@kernel.org> - 2017-08-30 16:30 +0200

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