From: Rik van Riel <riel@redhat.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
lkml <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero page in LRU list.
Date: Sun, 27 Dec 2009 22:22:20 -0500 [thread overview]
Message-ID: <4B38246C.3020209@redhat.com> (raw)
In-Reply-To: <20091228115315.76b1ecd0.minchan.kim@barrios-desktop>
On 12/27/2009 09:53 PM, Minchan Kim wrote:
>
> VM doesn't add zero page to LRU list.
> It means zero page's churning in LRU list is pointless.
>
> As a matter of fact, zero page can't be promoted by mark_page_accessed
> since it doesn't have PG_lru.
>
> This patch prevent unecessary mark_page_accessed call of zero page
> alghouth caller want FOLL_TOUCH.
>
> Signed-off-by: Minchan Kim<minchan.kim@gmail.com>
The code looks correct, but I wonder how frequently we run into
the zero page in this code, vs. how much the added cost is of
having this extra code in follow_page.
What kind of problem were you running into that motivated you
to write this patch?
--
All rights reversed.
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
lkml <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero page in LRU list.
Date: Sun, 27 Dec 2009 22:22:20 -0500 [thread overview]
Message-ID: <4B38246C.3020209@redhat.com> (raw)
In-Reply-To: <20091228115315.76b1ecd0.minchan.kim@barrios-desktop>
On 12/27/2009 09:53 PM, Minchan Kim wrote:
>
> VM doesn't add zero page to LRU list.
> It means zero page's churning in LRU list is pointless.
>
> As a matter of fact, zero page can't be promoted by mark_page_accessed
> since it doesn't have PG_lru.
>
> This patch prevent unecessary mark_page_accessed call of zero page
> alghouth caller want FOLL_TOUCH.
>
> Signed-off-by: Minchan Kim<minchan.kim@gmail.com>
The code looks correct, but I wonder how frequently we run into
the zero page in this code, vs. how much the added cost is of
having this extra code in follow_page.
What kind of problem were you running into that motivated you
to write this patch?
--
All rights reversed.
--
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next prev parent reply other threads:[~2009-12-28 3:22 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-28 2:53 [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero page in LRU list Minchan Kim
2009-12-28 2:53 ` Minchan Kim
2009-12-28 2:57 ` KAMEZAWA Hiroyuki
2009-12-28 2:57 ` KAMEZAWA Hiroyuki
2009-12-28 3:18 ` KOSAKI Motohiro
2009-12-28 3:18 ` KOSAKI Motohiro
2009-12-28 3:22 ` Rik van Riel [this message]
2009-12-28 3:22 ` Rik van Riel
2009-12-28 3:56 ` Balbir Singh
2009-12-28 3:56 ` Balbir Singh
2009-12-28 3:57 ` Balbir Singh
2009-12-28 3:57 ` Balbir Singh
2009-12-28 4:12 ` Rik van Riel
2009-12-28 4:12 ` Rik van Riel
2009-12-28 4:17 ` Balbir Singh
2009-12-28 4:17 ` Balbir Singh
2009-12-28 4:09 ` Minchan Kim
2009-12-28 4:09 ` Minchan Kim
2009-12-30 17:03 ` Hugh Dickins
2009-12-30 17:03 ` Hugh Dickins
2009-12-31 2:26 ` Minchan Kim
2009-12-31 2:26 ` Minchan Kim
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