linux-kernel - Re: [PATCH] vmscan: move PGDEACTIVATE modification to shrink_active

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Date:	Thu, 27 Aug 2009 09:59:26 +0200
From:	Johannes Weiner <hannes@...xchg.org>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] vmscan: move PGDEACTIVATE modification to shrink_active_list()

On Thu, Aug 27, 2009 at 01:39:01PM +0900, KOSAKI Motohiro wrote:
> Pgmoved accounting in move_active_pages_to_lru() doesn't make any sense.
> it can be calculated in irq enabled area.
> 
> This patch move #-of-deactivating-pages calcution to shrink_active_list().
> Fortunatelly, it also kill one branch.
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

Ah, this looks familiar.

So the last version was dropped because of failures - I assume because
Andrew dropped the patch that converted to add_page_to_lru_list() and
nobody accounted the page-putback anymore (and a compiler error due to
referencing the then unexisting pgmoved variable).  And this version
does the accounting itself again, okay.

Reviewed-by: Johannes Weiner <hannes@...xchg.org>

	Hannes

> ---
>  mm/vmscan.c |   20 ++++++++++----------
>  1 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 848689a..9618170 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1270,7 +1270,6 @@ static void move_active_pages_to_lru(struct zone *zone,
>  				     struct list_head *list,
>  				     enum lru_list lru)
>  {
> -	unsigned long pgmoved = 0;
>  	struct pagevec pvec;
>  	struct page *page;
>  
> @@ -1284,7 +1283,6 @@ static void move_active_pages_to_lru(struct zone *zone,
>  
>  		list_move(&page->lru, &zone->lru[lru].list);
>  		mem_cgroup_add_lru_list(page, lru);
> -		pgmoved++;
>  
>  		if (!pagevec_add(&pvec, page) || list_empty(list)) {
>  			spin_unlock_irq(&zone->lru_lock);
> @@ -1294,9 +1292,6 @@ static void move_active_pages_to_lru(struct zone *zone,
>  			spin_lock_irq(&zone->lru_lock);
>  		}
>  	}
> -	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
> -	if (!is_active_lru(lru))
> -		__count_vm_events(PGDEACTIVATE, pgmoved);
>  }
>  
>  static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
> @@ -1311,6 +1306,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
>  	struct page *page;
>  	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
>  	unsigned long nr_rotated = 0;
> +	unsigned long nr_deactivated = 0;
>  
>  	lru_add_drain();
>  	spin_lock_irq(&zone->lru_lock);
> @@ -1365,12 +1361,18 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
>  
>  		ClearPageActive(page);	/* we are de-activating */
>  		list_add(&page->lru, &l_inactive);
> +		nr_deactivated++;
>  	}
>  
>  	/*
>  	 * Move pages back to the lru list.
>  	 */
>  	spin_lock_irq(&zone->lru_lock);
> +	move_active_pages_to_lru(zone, &l_active,
> +						LRU_ACTIVE + file * LRU_FILE);
> +	move_active_pages_to_lru(zone, &l_inactive,
> +						LRU_BASE   + file * LRU_FILE);
> +
>  	/*
>  	 * Count referenced pages from currently used mappings as rotated,
>  	 * even though only some of them are actually re-activated.  This
> @@ -1378,12 +1380,10 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
>  	 * get_scan_ratio.
>  	 */
>  	reclaim_stat->recent_rotated[file] += nr_rotated;
> -
> -	move_active_pages_to_lru(zone, &l_active,
> -						LRU_ACTIVE + file * LRU_FILE);
> -	move_active_pages_to_lru(zone, &l_inactive,
> -						LRU_BASE   + file * LRU_FILE);
> +	__count_vm_events(PGDEACTIVATE, nr_deactivated);
>  	__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
> +	__mod_zone_page_state(zone, LRU_ACTIVE + file * LRU_FILE, nr_rotated);
> +	__mod_zone_page_state(zone, LRU_BASE + file * LRU_FILE, nr_deactivated);
>  	spin_unlock_irq(&zone->lru_lock);
>  }
>  
> -- 
> 1.6.2.5
> 
> 
> 
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