From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-mm@kvack.org, ak@suse.de, pj@sgi.com, kravetz@us.ibm.com,
marcelo.tosatti@cyclades.com, taka@valinux.co.jp,
lee.schermerhorn@hp.com, haveblue@us.ibm.com
Subject: Re: Status and the future of page migration
Date: Fri, 12 May 2006 11:08:25 +0900 [thread overview]
Message-ID: <20060512110825.7a49f17d.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0605111841060.17334@schroedinger.engr.sgi.com>
On Thu, 11 May 2006 18:43:13 -0700 (PDT)
Christoph Lameter <clameter@sgi.com> wrote:
> > > You are right but there may be system components (such as device drivers)
> > > that require the page not to be moved. Without page migration VM_LOCKED
> > > implies that the physical address stays the same. Kernel code may assume
> > > that VM_LOCKED -> dont migrate.
> > >
> > Hmm.. I think such pages should have extra refcnt to prevent migration.
>
> refcnts are for temporary use. An extra refcnt will make page migration
> retry until it gives up. It should not try to migrate an unmovable page.
>
Hmm...it seems the kernel drivers assumes the pages will not moved if VM_LOCKED.
I'm not sure which is better to replace all driver's VM_LOCKED to VM_DONTMOVE or
to add VM_KEEPONMEMORY for mlock() codes and just modify the kernel core.
-Kame
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next prev parent reply other threads:[~2006-05-12 2:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-12 0:06 Christoph Lameter
2006-05-12 0:56 ` KAMEZAWA Hiroyuki
2006-05-12 1:06 ` Christoph Lameter
2006-05-12 1:35 ` KAMEZAWA Hiroyuki
2006-05-12 1:43 ` Christoph Lameter
2006-05-12 2:08 ` KAMEZAWA Hiroyuki [this message]
2006-05-12 3:21 ` Christoph Lameter
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