From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Christoph Lameter <cl@linux.com>
Cc: kosaki.motohiro@jp.fujitsu.com,
Lee Schermerhorn <lee.schermerhorn@hp.com>,
linux-numa@vger.kernel.org, akpm@linux-foundation.org,
Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
Hugh Dickins <hughd@google.com>,
andi@firstfloor.org, David Rientjes <rientjes@google.com>,
Avi Kivity <avi@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH/RFC 0/8] numa - Migrate-on-Fault
Date: Tue, 16 Nov 2010 13:54:01 +0900 (JST) [thread overview]
Message-ID: <20101116134644.BF21.A69D9226@jp.fujitsu.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1011150809030.19175@router.home>
> On Sun, 14 Nov 2010, KOSAKI Motohiro wrote:
>
> > Nice!
>
> Lets not get overenthused. There has been no conclusive proof that the
> overhead introduced by automatic migration schemes is consistently less
> than the benefit obtained by moving the data. Quite to the contrary. We
> have over a decades worth of research and attempts on this issue and there
> was no general improvement to be had that way.
>
> The reason that the manual placement interfaces exist is because there was
> no generally beneficial migration scheme available. The manual interfaces
> allow the writing of various automatic migrations schemes in user space.
>
> If wecan come up with something that is an improvement then lets go
> this way but I am skeptical.
Ah, I thought this series only has manua migration (i.e. MPOL_MF_LAZY),
but it also has automatic migration if a page is not mapped. So my standpoint
is, manual lazy migration has certinally usecase. but I have no opinion against
automatic one.
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next prev parent reply other threads:[~2010-11-16 4:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20101111194450.12535.12611.sendpatchset@zaphod.localdomain>
[not found] ` <20101114152440.E02E.A69D9226@jp.fujitsu.com>
[not found] ` <alpine.DEB.2.00.1011150809030.19175@router.home>
2010-11-15 14:21 ` Andi Kleen
2010-11-15 14:37 ` Andrea Arcangeli
2010-11-16 4:54 ` KOSAKI Motohiro [this message]
2010-11-17 14:45 ` Lee Schermerhorn
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