linux-kernel - Re: [PATCH] vmscan: prevent background aging of anon page in no swap system

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Message-ID: <4C7A8173.5060306@redhat.com>
Date:	Sun, 29 Aug 2010 11:49:07 -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>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Ying Han <yinghan@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH] vmscan: prevent background aging of anon page in no swap
 system

On 08/29/2010 11:43 AM, Minchan Kim wrote:

> This patch prevents unnecessary anon pages demotion in not-swapon and
> non-configured swap system. Of course, it could make side effect that
> hot anon pages could swap out when admin does swap on.
> But I think sooner or later it would be steady state.
> So it's not a big problem.
> We could lose someting but gain more thing(TLB flush and unnecessary
> function call to demote anon pages).

A agree that is not a big worry.  I expect virtually all the
systems with swap space will do swapon at boot time.

> I used total_swap_pages because we want to age anon pages
> even though swap full happens.
>
> Cc: Rik van Riel<riel@...hat.com>
> Cc: KOSAKI Motohiro<kosaki.motohiro@...fujitsu.com>
> Cc: Johannes Weiner<hannes@...xchg.org>
> Reported-by: Ying Han<yinghan@...gle.com>
> Signed-off-by: Minchan Kim<minchan.kim@...il.com>

Reviewed-by: Rik van Riel <riel@...hat.com>

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