From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13F0FC63777 for ; Thu, 3 Dec 2020 10:53:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 53F59208A9 for ; Thu, 3 Dec 2020 10:53:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53F59208A9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C19876B005C; Thu, 3 Dec 2020 05:53:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BF0B96B006E; Thu, 3 Dec 2020 05:53:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ADF1D6B0070; Thu, 3 Dec 2020 05:53:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0166.hostedemail.com [216.40.44.166]) by kanga.kvack.org (Postfix) with ESMTP id 999BA6B005C for ; Thu, 3 Dec 2020 05:53:17 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5D3933628 for ; Thu, 3 Dec 2020 10:53:17 +0000 (UTC) X-FDA: 77551659234.17.rice47_1c124e2273bb Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 4D2A2180D0185 for ; Thu, 3 Dec 2020 10:53:17 +0000 (UTC) X-HE-Tag: rice47_1c124e2273bb X-Filterd-Recvd-Size: 2923 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Dec 2020 10:53:16 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 65793ACBA; Thu, 3 Dec 2020 10:53:15 +0000 (UTC) Date: Thu, 3 Dec 2020 10:53:13 +0000 From: Mel Gorman To: Peter Zijlstra Cc: Huang Ying , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Ingo Molnar , Rik van Riel , Johannes Weiner , "Matthew Wilcox (Oracle)" , Dave Hansen , Andi Kleen , Michal Hocko , David Rientjes , linux-api@vger.kernel.org Subject: Re: [PATCH -V6 RESEND 1/3] numa balancing: Migrate on fault among multiple bound nodes Message-ID: <20201203105313.GF3306@suse.de> References: <20201202084234.15797-1-ying.huang@intel.com> <20201202084234.15797-2-ying.huang@intel.com> <20201202114054.GV3306@suse.de> <20201203102550.GK2414@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20201203102550.GK2414@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Dec 03, 2020 at 11:25:50AM +0100, Peter Zijlstra wrote: > On Wed, Dec 02, 2020 at 11:40:54AM +0000, Mel Gorman wrote: > > On Wed, Dec 02, 2020 at 04:42:32PM +0800, Huang Ying wrote: > > > Now, NUMA balancing can only optimize the page placement among the > > > NUMA nodes if the default memory policy is used. Because the memory > > > policy specified explicitly should take precedence. But this seems > > > too strict in some situations. For example, on a system with 4 NUMA > > > nodes, if the memory of an application is bound to the node 0 and 1, > > > NUMA balancing can potentially migrate the pages between the node 0 > > > and 1 to reduce cross-node accessing without breaking the explicit > > > memory binding policy. > > > > > > > Ok, I think this part is ok and while the test case is somewhat > > superficial, it at least demonstrated that the NUMA balancing overhead > > did not offset any potential benefit > > > > Acked-by: Mel Gorman > > Who do we expect to merge this, me through tip/sched/core or akpm ? I would expect akpm, it's much more on the mm side because it affects the semantics of memory policies. It should also have more mm-orientated review than just mine because it affects user-visible semantics and the ability to detect whether the feature is available or not needs to be treated with care. -- Mel Gorman SUSE Labs