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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 ED7F6C742C7 for ; Fri, 12 Jul 2019 15:00:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6CC020863 for ; Fri, 12 Jul 2019 15:00:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562943613; bh=3Vz3kv/6WjEWjL5F1iANnnb8G0FIDp6WOEIqcfvYXw8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=gyEkH4dUc7UpAt7S54AbtXvegT4+SW0c2ZTvHmUMSam6z0E8PqhKe7YLYNEP5LGXw oDsXgvMDNfD5kolQLUutpjaYOzQE+taqyWqtFX9zUOp0jSq/1t4hlmOmJKckwt+ani TXLY0IN4Tm1/9pHryEcd6ufLewrzY8It68txjxEk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727076AbfGLPAM (ORCPT ); Fri, 12 Jul 2019 11:00:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:50336 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726466AbfGLPAL (ORCPT ); Fri, 12 Jul 2019 11:00:11 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id C4457ABE9; Fri, 12 Jul 2019 15:00:09 +0000 (UTC) Date: Fri, 12 Jul 2019 17:00:07 +0200 From: Michal Hocko To: Will Deacon Cc: Hoan Tran OS , Catalin Marinas , Heiko Carstens , "open list:MEMORY MANAGEMENT" , Paul Mackerras , "H . Peter Anvin" , "sparclinux@vger.kernel.org" , Alexander Duyck , "linux-s390@vger.kernel.org" , Michael Ellerman , "x86@kernel.org" , Mike Rapoport , Christian Borntraeger , Ingo Molnar , Vlastimil Babka , Benjamin Herrenschmidt , Open Source Submission , Pavel Tatashin , Vasily Gorbik , Will Deacon , Borislav Petkov , Thomas Gleixner , "linux-arm-kernel@lists.infradead.org" , Oscar Salvador , "linux-kernel@vger.kernel.org" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , "David S . Miller" , willy@infradead.org Subject: Re: [PATCH v2 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA Message-ID: <20190712150007.GU29483@dhcp22.suse.cz> References: <1562887528-5896-1-git-send-email-Hoan@os.amperecomputing.com> <20190712070247.GM29483@dhcp22.suse.cz> <586ae736-a429-cf94-1520-1a94ffadad88@os.amperecomputing.com> <20190712121223.GR29483@dhcp22.suse.cz> <20190712143730.au3662g4ua2tjudu@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190712143730.au3662g4ua2tjudu@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 12-07-19 15:37:30, Will Deacon wrote: > Hi all, > > On Fri, Jul 12, 2019 at 02:12:23PM +0200, Michal Hocko wrote: > > On Fri 12-07-19 10:56:47, Hoan Tran OS wrote: > > [...] > > > It would be good if we can enable it by-default. Otherwise, let arch > > > enables it by them-self. Do you have any suggestions? > > > > I can hardly make any suggestions when it is not really clear _why_ you > > want to remove this config option in the first place. Please explain > > what motivated you to make this change. > > Sorry, I think this confusion might actually be my fault and Hoan has just > been implementing my vague suggestion here: > > https://lore.kernel.org/linux-arm-kernel/20190625101245.s4vxfosoop52gl4e@willie-the-truck/ > > If the preference of the mm folks is to leave CONFIG_NODES_SPAN_OTHER_NODES > as it is, then we can define it for arm64. I just find it a bit weird that > the majority of NUMA-capable architectures have to add a symbol in the arch > Kconfig file, for what appears to be a performance optimisation applicable > only to ia64, mips and sh. > > At the very least we could make the thing selectable. Hmm, I thought this was selectable. But I am obviously wrong here. Looking more closely, it seems that this is indeed only about __early_pfn_to_nid and as such not something that should add a config symbol. This should have been called out in the changelog though. Also while at it, does HAVE_MEMBLOCK_NODE_MAP fall into a similar bucket? Do we have any NUMA architecture that doesn't enable it? Thanks! -- Michal Hocko SUSE Labs