From: Andrea Arcangeli <aarcange@redhat.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Izik Eidus <ieidus@redhat.com>, Chris Wright <chrisw@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/9] ksm: let shared pages be swappable
Date: Fri, 4 Dec 2009 15:49:08 +0100 [thread overview]
Message-ID: <20091204144908.GJ28697@random.random> (raw)
In-Reply-To: <20091204141617.f4c491e7.kamezawa.hiroyu@jp.fujitsu.com>
On Fri, Dec 04, 2009 at 02:16:17PM +0900, KAMEZAWA Hiroyuki wrote:
> Hmm, can't we use ZERO_PAGE we have now ?
> If do so,
> - no mapcount check
> - never on LRU
> - don't have to maintain shared information because ZERO_PAGE itself has
> copy-on-write nature.
The zero page could be added to the stable tree always to avoid a
memcmp and we could try to merge anon pages into it, instead of
merging it into ksmpages, but it's not a ksm page so it would require
special handling with branches. We considered doing a magic on
zeropage but we though it's not worth it. We need CPU to be efficient
on very shared pages not just zero page without magics, and the memory
saving is just 4k system-wide (all zero pages of all windows are
already shared).
--
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next prev parent reply other threads:[~2009-12-04 14:49 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-24 16:37 [PATCH 0/9] ksm: swapping Hugh Dickins
2009-11-24 16:40 ` [PATCH 1/9] ksm: fix mlockfreed to munlocked Hugh Dickins
2009-11-24 23:53 ` Rik van Riel
2009-11-26 16:20 ` Mel Gorman
2009-11-27 12:45 ` Hugh Dickins
2009-11-30 6:01 ` KOSAKI Motohiro
2009-11-30 12:26 ` Hugh Dickins
2009-11-30 21:27 ` Lee Schermerhorn
2009-12-01 11:14 ` Mel Gorman
2009-11-24 16:42 ` [PATCH 2/9] ksm: let shared pages be swappable Hugh Dickins
2009-11-30 0:46 ` KAMEZAWA Hiroyuki
2009-11-30 9:15 ` KOSAKI Motohiro
2009-11-30 12:38 ` Hugh Dickins
2009-12-01 4:14 ` KOSAKI Motohiro
2009-11-30 11:55 ` Hugh Dickins
2009-11-30 12:07 ` Andrea Arcangeli
2009-12-01 0:39 ` KAMEZAWA Hiroyuki
2009-12-01 6:32 ` Chris Wright
2009-12-01 9:11 ` Andrea Arcangeli
2009-12-01 9:28 ` KOSAKI Motohiro
2009-12-01 9:37 ` Andrea Arcangeli
2009-12-01 9:46 ` KOSAKI Motohiro
2009-12-01 9:59 ` Andrea Arcangeli
2009-12-02 5:08 ` Rik van Riel
2009-12-02 12:55 ` Andrea Arcangeli
2009-12-03 5:15 ` KOSAKI Motohiro
2009-12-04 5:06 ` KOSAKI Motohiro
2009-12-04 5:16 ` KAMEZAWA Hiroyuki
2009-12-04 14:49 ` Andrea Arcangeli [this message]
2009-12-04 17:16 ` Chris Wright
2009-12-04 18:53 ` Andrea Arcangeli
2009-12-04 19:03 ` Chris Wright
2009-12-09 0:43 ` KAMEZAWA Hiroyuki
2009-12-09 1:04 ` Chris Wright
2009-12-09 16:12 ` Andrea Arcangeli
2009-12-09 23:54 ` KAMEZAWA Hiroyuki
2009-12-04 14:45 ` Andrea Arcangeli
2009-12-04 16:21 ` Rik van Riel
2009-11-24 16:43 ` [PATCH 3/9] ksm: hold anon_vma in rmap_item Hugh Dickins
2009-11-24 16:45 ` [PATCH 4/9] ksm: take keyhole reference to page Hugh Dickins
2009-11-24 16:48 ` [PATCH 5/9] ksm: share anon page without allocating Hugh Dickins
2009-11-30 0:04 ` KAMEZAWA Hiroyuki
2009-11-30 11:18 ` Hugh Dickins
2009-12-01 0:02 ` KAMEZAWA Hiroyuki
2009-11-24 16:51 ` [PATCH 6/9] ksm: mem cgroup charge swapin copy Hugh Dickins
2009-11-25 14:23 ` Balbir Singh
2009-11-25 17:12 ` Hugh Dickins
2009-11-25 17:36 ` Balbir Singh
2009-11-30 0:13 ` KAMEZAWA Hiroyuki
2009-11-30 11:40 ` Hugh Dickins
2009-11-24 16:54 ` [PATCH 7/9] ksm: rmap_walk to remove_migation_ptes Hugh Dickins
2009-11-24 16:56 ` [PATCH 8/9] ksm: memory hotremove migration only Hugh Dickins
2009-11-24 16:57 ` [PATCH 9/9] ksm: remove unswappable max_kernel_pages Hugh Dickins
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