From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 439B18D0080 for ; Mon, 15 Nov 2010 23:54:09 -0500 (EST) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id oAG4s6YB032040 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 16 Nov 2010 13:54:06 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 525A145DE55 for ; Tue, 16 Nov 2010 13:54:06 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 312CF45DE4E for ; Tue, 16 Nov 2010 13:54:06 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 127E2E08003 for ; Tue, 16 Nov 2010 13:54:06 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id C524EE08002 for ; Tue, 16 Nov 2010 13:54:02 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH/RFC 0/8] numa - Migrate-on-Fault In-Reply-To: References: <20101114152440.E02E.A69D9226@jp.fujitsu.com> Message-Id: <20101116134644.BF21.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Tue, 16 Nov 2010 13:54:01 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: kosaki.motohiro@jp.fujitsu.com, Lee Schermerhorn , linux-numa@vger.kernel.org, akpm@linux-foundation.org, Mel Gorman , Nick Piggin , Hugh Dickins , andi@firstfloor.org, David Rientjes , Avi Kivity , Andrea Arcangeli , linux-mm List-ID: > 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org