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Message-ID: <28c262360906110239g1e4d0fabg15dc33111014e96a@mail.gmail.com>
Date: Thu, 11 Jun 2009 18:39:01 +0900
From: Minchan Kim <minchan.kim@...il.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
apw@...onical.com, riel@...hat.com, mel@....ul.ie
Subject: Re: [PATCH 2/3] check unevictable flag in lumy reclaim v2
On Thu, Jun 11, 2009 at 6:37 PM, Minchan Kim<minchan.kim@...il.com> wrote:
> On Thu, Jun 11, 2009 at 5:38 PM, KAMEZAWA
> Hiroyuki<kamezawa.hiroyu@...fujitsu.com> wrote:
>> How about this ?
>>
>> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>>
>> Lumpy reclaim check pages from their pfn. Then, it can find unevictable pages
>> in its loop.
>> Abort lumpy reclaim when we find Unevictable page, we never get a lump
>> of pages for requested order.
>>
>> Changelog: v1->v2
>> - rewrote commet.
>>
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>> ---
>> mm/vmscan.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> Index: lumpy-reclaim-trial/mm/vmscan.c
>> ===================================================================
>> --- lumpy-reclaim-trial.orig/mm/vmscan.c
>> +++ lumpy-reclaim-trial/mm/vmscan.c
>> @@ -936,6 +936,15 @@ static unsigned long isolate_lru_pages(u
>> /* Check that we have not crossed a zone boundary. */
>> if (unlikely(page_zone_id(cursor_page) != zone_id))
>> continue;
>> + /*
>> + * We tries to free all pages in this range to create
>> + * a free large page. Then, if the range includes a page
>> + * never be reclaimed, we have no reason to do more.
>> + * PageUnevictable page is not a page which can be
>> + * easily freed. Abort this scan now.
>> + */
>> + if (unlikely(PageUnevictable(cursor_page)))
>> + break;
>
> __isolate_lru_pages already checked PageUnevictable to return error.
> I want to remove repeated check although it is trivial.
>
> By your patch, It seems to remove PageUnevictable check in __isolate_lru_pages.
typo.
It seems we can remove PageUnevictable check in __isolate_lru_pages.
Sorry for noise.
> But I know that. If we remove PageUnevictable check in
> __isolate_lru_pages, it can't go into BUG in non-lumpy case. ( I
> mentioned following as code)
>
> case -EBUSY:
> /* else it is being freed elsewhere */
> list_move(&page->lru, src);
> continue;
>
> default:
> BUG();
> }
>
>
> It means we can remove BUG in non-lumpy case and then add BUG into
> __isolate_lru_pages directly.
>
> If we can do it, we can remove unnecessary PageUnevictable check in
> __isolate_lru_page.
>
> I am not sure this is right in case of memcg.
>
> --
> Kinds regards,
> Minchan Kim
>
--
Kinds regards,
Minchan Kim
--
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