linux-kernel - Re: [patch 2/8] mm: memcg: remove mem_cgroup_move_account_page

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Date:	Mon, 10 Feb 2014 15:19:54 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 2/8] mm: memcg: remove mem_cgroup_move_account_page_stat()

On Fri 07-02-14 12:04:19, Johannes Weiner wrote:
> It used to disable preemption and run sanity checks but now it's only
> taking a number out of one percpu counter and putting it into another.
> Do this directly in the callsite and save the indirection.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

OK, why not.
Acked-by: Michal Hocko <mhocko@...e.cz>

> ---
>  mm/memcontrol.c | 28 ++++++++++++----------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index befb3dd9d46c..639cf58b2643 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3776,16 +3776,6 @@ void mem_cgroup_split_huge_fixup(struct page *head)
>  }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
> -static void mem_cgroup_move_account_page_stat(struct mem_cgroup *from,
> -					      struct mem_cgroup *to,
> -					      unsigned int nr_pages,
> -					      enum mem_cgroup_stat_index idx)
> -{
> -	/* Update stat data for mem_cgroup */
> -	__this_cpu_sub(from->stat->count[idx], nr_pages);
> -	__this_cpu_add(to->stat->count[idx], nr_pages);
> -}
> -
>  /**
>   * mem_cgroup_move_account - move account of the page
>   * @page: the page
> @@ -3831,13 +3821,19 @@ static int mem_cgroup_move_account(struct page *page,
>  
>  	move_lock_mem_cgroup(from, &flags);
>  
> -	if (!anon && page_mapped(page))
> -		mem_cgroup_move_account_page_stat(from, to, nr_pages,
> -			MEM_CGROUP_STAT_FILE_MAPPED);
> +	if (!anon && page_mapped(page)) {
> +		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
> +			       nr_pages);
> +		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
> +			       nr_pages);
> +	}
>  
> -	if (PageWriteback(page))
> -		mem_cgroup_move_account_page_stat(from, to, nr_pages,
> -			MEM_CGROUP_STAT_WRITEBACK);
> +	if (PageWriteback(page)) {
> +		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_WRITEBACK],
> +			       nr_pages);
> +		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_WRITEBACK],
> +			       nr_pages);
> +	}
>  
>  	mem_cgroup_charge_statistics(from, page, anon, -nr_pages);
>  
> -- 
> 1.8.5.3
> 

-- 
Michal Hocko
SUSE Labs
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