linux-kernel - Re: [PATCH -mm 07/16] second chance replacement for anonymous pages

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Date:	Wed, 28 May 2008 14:36:56 +0900
From:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
To:	Rik van Riel <riel@...hat.com>
CC:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lee Schermerhorn <lee.schermerhorn@...com>,
	Kosaki Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH -mm 07/16] second chance replacement for anonymous pages

Hi.

> @@ -1008,7 +1008,7 @@ static inline int zone_is_near_oom(struc
>  static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
>  			struct scan_control *sc, int priority, int file)
>  {
> -	unsigned long pgmoved;
> +	unsigned long pgmoved = 0;
>  	int pgdeactivate = 0;
>  	unsigned long pgscanned;
>  	LIST_HEAD(l_hold);	/* The pages which were snipped off */
> @@ -1040,13 +1040,25 @@ static void shrink_active_list(unsigned 
>  		cond_resched();
>  		page = lru_to_page(&l_hold);
>  		list_del(&page->lru);
> -		if (page_referenced(page, 0, sc->mem_cgroup))
> +		if (page_referenced(page, 0, sc->mem_cgroup) && file) {
> +			/* Referenced file pages stay active. */
>  			list_add(&page->lru, &l_active);
> -		else
> +		} else {
>  			list_add(&page->lru, &l_inactive);
> +			if (!file)
> +				/* Anonymous pages always get deactivated. */
> +				pgmoved++;
> +		}
>  	}
>  
>  	/*
> +	 * Count the referenced anon pages as rotated, to balance pageout
> +	 * scan pressure between file and anonymous pages in get_sacn_ratio.
> +	 */
> +	if (!file)
> +		zone->recent_rotated_anon += pgmoved;
> +

Shouldn't 'pgmoved' be cleared to 0 before scanning l_hold?
It's used to store the result of sc->isolate_pages() before
scanning l_hold.


Thanks,
Daisuke Nishimura.

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