linux-kernel - Re: [PATCH 2/2] vmscan: activate executable pages after first usage

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Date:	Tue, 9 Aug 2011 09:02:28 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Wu Fengguang <fengguang.wu@...el.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH 2/2] vmscan: activate executable pages after first usage

On Mon, Aug 8, 2011 at 8:07 PM, Konstantin Khlebnikov
<khlebnikov@...nvz.org> wrote:
> Logic added in commit v2.6.30-5507-g8cab475
> (vmscan: make mapped executable pages the first class citizen)
> was noticeably weakened in commit v2.6.33-5448-g6457474
> (vmscan: detect mapped file pages used only once)
>
> Currently these pages can become "first class citizens" only after second usage.
>
> After this patch page_check_references() will activate they after first usage,
> and executable code gets yet better chance to stay in memory.
>
> TODO:
> run some cool tests like in v2.6.30-5507-g8cab475 =)
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
> ---

It might be a very controversial topic.
AFAIR, at least, we did when vmscan: make mapped executable pages the
first class citizen was merged. :)

You try to change behavior.

Old : protect *working set* executable page
New: protect executable page *unconditionally*.

At least, old logic can ignore some executable pages which are not
accessed recently.

Wu had many testing to persuade others.
As you said, we need some number to change policy.

-- 
Kind regards,
Minchan Kim
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