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

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Message-ID: <BANLkTinq7w+cejBgBMuWvGw9htK0YJOvEw@mail.gmail.com>
Date:	Wed, 27 Apr 2011 17:12:19 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.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, Apr 27, 2011 at 4:54 PM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
> 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 ?

Yes. Even I added new flags one more in next patch.
So I try to use bitmask flag in next version.
Thanks.


>
> Thanks,
> -Kame
>
>



-- 
Kind regards,
Minchan Kim
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