From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Konrad Wilk <konrad.wilk@oracle.com>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
Nitin Gupta <ngupta@vflare.org>,
Nebojsa Trpkovic <trx.lists@gmail.com>,
minchan@kernel.org,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
riel@redhat.com, Chris Mason <chris.mason@oracle.com>
Subject: Re: [PATCH] mm: implement WasActive page flag (for improving cleancache)
Date: Thu, 26 Jan 2012 09:28:22 -0800 [thread overview]
Message-ID: <4F218D36.2060308@linux.vnet.ibm.com> (raw)
In-Reply-To: <ea3b0850-dfe0-46db-9201-2bfef110848d@default>
On 01/25/2012 01:58 PM, Dan Magenheimer wrote:
> (Feedback welcome if there is a different/better way to do this
> without using a page flag!)
>
> Since about 2.6.27, the page replacement algorithm maintains
> an "active" bit to help decide which pages are most eligible
> to reclaim, see http://linux-mm.org/PageReplacementDesign
>
> This "active' information is also useful to cleancache but is lost
> by the time that cleancache has the opportunity to preserve the
> pageful of data. This patch adds a new page flag "WasActive" to
> retain the state. The flag may possibly be useful elsewhere.
I guess cleancache itself is clearing the bit, right? I didn't see any
clearing going on in the patch.
I do think it also needs to get cleared on the way in to the page
allocator. Otherwise:
PageSetWasActive(page);
free_page(page);
...
another_user_page = get_free_page()
// now cleancache sees the active bit for the prev user
Or am I missing somewhere it gets cleared non-explicitly somewhere?
next prev parent reply other threads:[~2012-01-26 17:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-25 21:58 [PATCH] mm: implement WasActive page flag (for improving cleancache) Dan Magenheimer
2012-01-26 17:28 ` Dave Hansen [this message]
2012-01-26 21:28 ` Dan Magenheimer
2012-01-27 0:31 ` Andrew Morton
2012-01-27 0:56 ` Dan Magenheimer
2012-01-27 1:15 ` Andrew Morton
2012-01-27 2:43 ` Dan Magenheimer
2012-01-27 3:33 ` Rik van Riel
2012-01-27 5:15 ` Dan Magenheimer
2012-01-30 8:57 ` KAMEZAWA Hiroyuki
2012-01-30 22:03 ` Dan Magenheimer
2012-01-27 13:43 ` James Bottomley
2012-01-27 17:32 ` Dan Magenheimer
2012-01-27 17:54 ` James Bottomley
2012-01-27 18:46 ` Dan Magenheimer
2012-01-27 21:49 ` James Bottomley
2012-01-29 0:50 ` Rik van Riel
2012-01-29 22:25 ` James Bottomley
2012-01-27 3:28 ` Rik van Riel
2012-01-27 5:11 ` Dan Magenheimer
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