linux-kernel - Re: [RFC 1/8] Only isolate page we can handle

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Message-Id: <20110427165437.bef6967a.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 27 Apr 2011 16:54:37 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.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>,
	Christoph Lameter <cl@...ux.com>,
	Johannes Weiner <jweiner@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC 1/8] Only isolate page we can handle

On Wed, 27 Apr 2011 01:25:18 +0900
Minchan Kim <minchan.kim@...il.com> wrote:

> There are some places to isolate lru page and I believe
> users of isolate_lru_page will be growing.
> The purpose of them is each different so part of isolated pages
> should put back to LRU, again.
> 
> The problem is when we put back the page into LRU,
> we lose LRU ordering and the page is inserted at head of LRU list.
> It makes unnecessary LRU churning so that vm can evict working set pages
> rather than idle pages.
> 
> This patch adds new filter mask when we isolate page in LRU.
> So, we don't isolate pages if we can't handle it.
> It could reduce LRU churning.
> 
> This patch shouldn't change old behavior.
> It's just used by next patches.
> 
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Rik van Riel <riel@...hat.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Minchan Kim <minchan.kim@...il.com>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

nitpick below.

> ---
>  include/linux/swap.h |    3 ++-
>  mm/compaction.c      |    2 +-
>  mm/memcontrol.c      |    2 +-
>  mm/vmscan.c          |   26 ++++++++++++++++++++------
>  4 files changed, 24 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 384eb5f..baef4ad 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -259,7 +259,8 @@ extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
>  						unsigned int swappiness,
>  						struct zone *zone,
>  						unsigned long *nr_scanned);
> -extern int __isolate_lru_page(struct page *page, int mode, int file);
> +extern int __isolate_lru_page(struct page *page, int mode, int file,
> +				int not_dirty, int not_mapped);

Hmm, which is better to use 4 binary args or a flag with bitmask ?

Thanks,
-Kame

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