linux-kernel - Re: [RFC 3/8] vmscan: make isolate_lru

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Message-ID: <BANLkTi=kLjZRp+kxrhG8Q-bEFw7x-O6vgg@mail.gmail.com>
Date:	Sat, 30 Apr 2011 00:18:02 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Mel Gorman <mgorman@...e.de>
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>,
	Rik van Riel <riel@...hat.com>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [RFC 3/8] vmscan: make isolate_lru_page with filter aware

On Thu, Apr 28, 2011 at 7:35 PM, Mel Gorman <mgorman@...e.de> wrote:
> On Wed, Apr 27, 2011 at 01:25:20AM +0900, Minchan Kim wrote:
>> In some __zone_reclaim case, we don't want to shrink mapped page.
>> Nonetheless, we have isolated mapped page and re-add it into
>> LRU's head. It's unnecessary CPU overhead and makes LRU churning.
>>
>> Of course, when we isolate the page, the page might be mapped but
>> when we try to migrate the page, the page would be not mapped.
>> So it could be migrated. But race is rare and although it happens,
>> it's no big deal.
>>
>> Cc: Christoph Lameter <cl@...ux.com>
>> 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>
>
>> index 71d2da9..e8d6190 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1147,7 +1147,8 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>>
>>  static unsigned long isolate_pages_global(unsigned long nr,
>>                                       struct list_head *dst,
>> -                                     unsigned long *scanned, int order,
>> +                                     unsigned long *scanned,
>> +                                     struct scan_control *sc,
>>                                       int mode, struct zone *z,
>>                                       int active, int file)
>>  {
>> @@ -1156,8 +1157,8 @@ static unsigned long isolate_pages_global(unsigned long nr,
>>               lru += LRU_ACTIVE;
>>       if (file)
>>               lru += LRU_FILE;
>> -     return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order,
>> -                                     mode, file, 0, 0);
>> +     return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, sc->order,
>> +                                     mode, file, 0, !sc->may_unmap);
>>  }
>>
>
> Why not take may_writepage into account for dirty pages?

I missed it.
I will consider it in next version.
Thanks, Mel.


-- 
Kind regards,
Minchan Kim
--
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