linux-kernel - Re: [PATCH 2/2] Filter unevictable page out in deactivate

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Date:	Mon, 02 May 2011 10:57:31 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Minchan Kim <minchan.kim@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Ying Han <yinghan@...gle.com>
Subject: Re: [PATCH 2/2] Filter unevictable page out in deactivate_page

On 05/01/2011 11:03 AM, Minchan Kim wrote:
> It's pointless that deactive_page's pagevec operation about
> unevictable page as it's nop.
> This patch removes unnecessary overhead which might be a bit problem
> in case that there are many unevictable page in system(ex, mprotect workload)
>
> Signed-off-by: Minchan Kim<minchan.kim@...il.com>
> ---
>   mm/swap.c |    9 +++++++++
>   1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index 2e9656d..b707694 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -511,6 +511,15 @@ static void drain_cpu_pagevecs(int cpu)
>    */
>   void deactivate_page(struct page *page)
>   {
> +
> +	/*
> +	 * In workload which system has many unevictable page(ex, mprotect),
> +	 * unevictalge page deactivation for accelerating reclaim

Typo.

> +	 * is pointless.
> +	 */
> +	if (PageUnevictable(page))
> +		return;
> +
>   	if (likely(get_page_unless_zero(page))) {
>   		struct pagevec *pvec =&get_cpu_var(lru_deactivate_pvecs);
>


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