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, URIBL_BLOCKED,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 BBE9DC4CECD for ; Tue, 17 Sep 2019 09:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89FEB20862 for ; Tue, 17 Sep 2019 09:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568713024; bh=Fe8XY02MKWVmUu0yJIS6DNTB2BQA7WdpsCervfWNCwc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=PWvrye60UJ3fRvWMjwYCJOSaCvc1DuxIYCOoJ3do+QfhzB4yyGvvZU6oB6htv1dVu KLO8+sa6+sJ3Lwdj9NyuyWQJMDVuph0PPBofO62xgGtHYeKD8UlY2e5nZkD4uh4E7x mhHvazIWKLtWEvEym+OMS7abSurAbDkj4BZYpVKU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728103AbfIQJhD (ORCPT ); Tue, 17 Sep 2019 05:37:03 -0400 Received: from mx2.suse.de ([195.135.220.15]:40034 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726191AbfIQJhC (ORCPT ); Tue, 17 Sep 2019 05:37:02 -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 E6DA5ACC6; Tue, 17 Sep 2019 09:36:58 +0000 (UTC) Date: Tue, 17 Sep 2019 11:36:55 +0200 From: Michal Hocko To: Yunsheng Lin Cc: Michael Ellerman , catalin.marinas@arm.com, will@kernel.org, mingo@redhat.com, bp@alien8.de, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, benh@kernel.crashing.org, paulus@samba.org, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, ralf@linux-mips.org, paul.burton@mips.com, jhogan@kernel.org, jiaxun.yang@flygoat.com, chenhc@lemote.com, akpm@linux-foundation.org, rppt@linux.ibm.com, anshuman.khandual@arm.com, tglx@linutronix.de, cai@lca.pw, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, hpa@zytor.com, x86@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, len.brown@intel.com, axboe@kernel.dk, dledford@redhat.com, jeffrey.t.kirsher@intel.com, linux-alpha@vger.kernel.org, naveen.n.rao@linux.vnet.ibm.com, mwb@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, tbogendoerfer@suse.de, linux-mips@vger.kernel.org, rafael@kernel.org, gregkh@linuxfoundation.org Subject: Re: [PATCH v5] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20190917093655.GA1872@dhcp22.suse.cz> References: <1568640481-133352-1-git-send-email-linyunsheng@huawei.com> <87pnjzsd8f.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Tue 17-09-19 14:20:11, Yunsheng Lin wrote: > On 2019/9/17 13:28, Michael Ellerman wrote: > > Yunsheng Lin writes: [...] > >> But we cannot really copy the page allocator logic. Simply because the > >> page allocator doesn't enforce the near node affinity. It just picks it > >> up as a preferred node but then it is free to fallback to any other numa > >> node. This is not the case here and node_to_cpumask_map will only restrict > >> to the particular node's cpus which would have really non deterministic > >> behavior depending on where the code is executed. So in fact we really > >> want to return cpu_online_mask for NUMA_NO_NODE. > >> > >> Some arches were already NUMA_NO_NODE aware, but they return cpu_all_mask, > >> which should be identical with cpu_online_mask when those arches do not > >> support cpu hotplug, this patch also changes them to return cpu_online_mask > >> in order to be consistent and use NUMA_NO_NODE instead of "-1". > > > > Except some of those arches *do* support CPU hotplug, powerpc and sparc > > at least. So switching from cpu_all_mask to cpu_online_mask is a > > meaningful change. > > Yes, thanks for pointing out. > > > > > That doesn't mean it's wrong, but you need to explain why it's the right > > change. > > How about adding the below to the commit log: > Even if some of the arches do support CPU hotplug, it does not make sense > to return the cpu that has been hotplugged. > > Any suggestion? Again, for the third time, I believe. Make it a separate patch please. There is absolutely no reason to conflate those two things. -- Michal Hocko SUSE Labs