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Date: Fri, 16 Apr 2010 01:02:08 +0900
Message-ID: <k2r28c262361004150902tff8e6d2fvc64bcdc496ba699e@mail.gmail.com>
Subject: Re: [PATCH] rmap: add exclusively owned pages to the newest anon_vma
From: Minchan Kim <minchan.kim@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Johannes Weiner <hannes@cmpxchg.org>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
       Nick Piggin <npiggin@suse.de>, Andrea Arcangeli <aarcange@redhat.com>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>, sgunderson@bigfoot.com
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On Thu, Apr 15, 2010 at 6:59 AM, Rik van Riel <riel@redhat.com> wrote:
> The recent anon_vma fixes cause many anonymous pages to end up
> in the parent process anon_vma, even when the page is exclusively
> owned by the current process.
>
> Adding exclusively owned anonymous pages to the top anon_vma
> reduces rmap scanning overhead, especially in workloads with
> forking servers.
>
> This patch adds a parameter to __page_set_anon_rmap that can
> be used to indicate whether or not the added page is exclusively
> owned by the current process.
>
> Pages added through page_add_new_anon_rmap are exclusively
> owned by the current process, and can be added to the top
> anon_vma.
>
> Pages added through page_add_anon_rmap can be either shared
> or exclusively owned, so we do the conservative thing and
> add it to the oldest anon_vma.
>
> A next step would be to add the exclusive parameter to
> page_add_anon_rmap, to be used from functions where we do
> know for sure whether a page is exclusively owned.
>
> Signed-off-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>


-- 
Kind regards,
Minchan Kim