linux-kernel - Re: [RFC 6/8] In order putback lru core

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Date:	Thu, 28 Apr 2011 08:59:17 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Rik van Riel <riel@...hat.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>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC 6/8] In order putback lru core

Hi Rik,

On Thu, Apr 28, 2011 at 8:46 AM, Rik van Riel <riel@...hat.com> wrote:
> On 04/26/2011 12:25 PM, Minchan Kim wrote:
>
>> But this approach has a problem on contiguous pages.
>> In this case, my idea can not work since friend pages are isolated, too.
>> It means prev_page->next == next_page always is false and both pages are
>> not
>> LRU any more at that time. It's pointed out by Rik at LSF/MM summit.
>> So for solving the problem, I can change the idea.
>> I think we don't need both friend(prev, next) pages relation but
>> just consider either prev or next page that it is still same LRU.
>
>> Any comment?
>
> If the friend pages are isolated too, then your condition
> "either prev or next page that it is still same LRU" is
> likely to be false, no?

H - P1 - P2 - P3 - P4 - P5 - P6 - P7 - P8 - P9 - P10 - T

assume : we isolate pages P3~P7 and we consider only next pointer.

H - P1 - P2 - P8 - P9 - P10 - T

If we start to putback P7 as starting point, next P8 is valid so,

H - P1 - P2 - P7 - P8 - P9 - P10 - T
Then, if we consider P6, next P7 is valid, too. So,

H - P1 - P2 - P6 - P7 - P8 - P9 - P10 - T

continue until P3.


-- 
Kind regards,
Minchan Kim
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