From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx132.postini.com [74.125.245.132]) by kanga.kvack.org (Postfix) with SMTP id E384B6B005A for ; Fri, 29 Jun 2012 16:44:17 -0400 (EDT) Received: by bkcjc3 with SMTP id jc3so1402294bkc.14 for ; Fri, 29 Jun 2012 13:44:16 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1340888180-15355-1-git-send-email-aarcange@redhat.com> <1340888180-15355-14-git-send-email-aarcange@redhat.com> <1340895238.28750.49.camel@twins> <20120629125517.GD32637@gmail.com> <4FEDDD0C.60609@redhat.com> <1340995986.28750.114.camel@twins> Date: Sat, 30 Jun 2012 04:44:15 +0800 Message-ID: Subject: Re: [PATCH 13/40] autonuma: CPU follow memory algorithm From: Nai Xia Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: dlaor@redhat.com, Ingo Molnar , Hillf Danton , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dan Smith , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Bharata B Rao , Lee Schermerhorn , Rik van Riel , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter , Alex Shi , Mauricio Faria de Oliveira , Konrad Rzeszutek Wilk , Don Morris , Benjamin Herrenschmidt On Sat, Jun 30, 2012 at 4:01 AM, Nai Xia wrote: > On Sat, Jun 30, 2012 at 2:53 AM, Peter Zijlstra = wrote: >> On Fri, 2012-06-29 at 12:51 -0400, Dor Laor wrote: >>> The previous comments were not shouts but the mother of all NAKs. >> >> I never said any such thing. I just said why should I bother reading >> your stuff if you're ignoring most my feedback anyway. >> >> If you want to read that as a NAK, not my problem. > > Hey guys, Can I say NAK to these patches ? > > Now I aware that this sampling algorithm is completely broken, if we take > a few seconds to see what it is trying to solve: > > We all know that LRU is try to solve the question of "what are the > pages recently accessed?", > so its engouth to use pte bits to approximate. > > However, the numa balancing problem is fundamentally like this: > > In some time unit, > > =A0 =A0 =A0W =3D pages_accessed =A0* =A0average_page_access_frequence > > We are trying to move process to the node having max W, =A0right? > > Andrea's patch can only approximate the pages_accessed number in a > time unit(scan interval), > I don't think it can catch even 1% of =A0average_page_access_frequence > on a busy workload. > Blindly assuming that all the pages' =A0average_page_access_frequence is Oh, sorry for my typo, I mean "frequency". > the same is seemly > broken to me. > > Sometimes, it's good to have a good view of your problem before > spending a lot time coding. > >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. =A0For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org -- 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/ . Don't email: email@kvack.org