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=unavailable 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 99700C71156 for ; Thu, 3 Dec 2020 10:54:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 486FE21D1A for ; Thu, 3 Dec 2020 10:54:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388909AbgLCKx5 (ORCPT ); Thu, 3 Dec 2020 05:53:57 -0500 Received: from mx2.suse.de ([195.135.220.15]:38628 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727007AbgLCKx5 (ORCPT ); Thu, 3 Dec 2020 05:53:57 -0500 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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