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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,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 C986FC432C1 for ; Tue, 24 Sep 2019 09:26:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B259214D9 for ; Tue, 24 Sep 2019 09:26:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lytUR31w" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504190AbfIXJ0r (ORCPT ); Tue, 24 Sep 2019 05:26:47 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46044 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2504189AbfIXJ0r (ORCPT ); Tue, 24 Sep 2019 05:26:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=jpxNL12cNMAZAoNUWd3gZZ5abGhJ0ftyATBAiZSxSQU=; b=lytUR31wG42Kx44xHl1Qi+HEP d503DtCrHlkpVkJIig01ou5wdkagxJ8pPFOrHUWRzivw14hEO0i4UUB6FjPb7GXcgyodvG9h5SM7O /Mm31MMJM8e6CfMCQDt4HjEPRMRCwAF5YwjiPfWs81M8jd3n/Rl5vYQXPyGdffdlg9EDzmC8+qdY/ uiwJ7MhOCy608Svimr/+uEstMd7G24lfij70nORC92UrTdg+CkE2IEzV9Fgl7prPY9UWbEwy5SSPF nzZkjyQy0GCM5v1NSmtubG67AIFpkW1pgFCB0OszOtjgX8e7Ama65wa8OgCnQiohUsv4HHh7IICil +ylXkIt3A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCh4z-0002RC-TG; Tue, 24 Sep 2019 09:25:54 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id E50D2305E35; Tue, 24 Sep 2019 11:25:05 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6FC1F20D80D41; Tue, 24 Sep 2019 11:25:51 +0200 (CEST) Date: Tue, 24 Sep 2019 11:25:51 +0200 From: Peter Zijlstra To: Yunsheng Lin Cc: Michal Hocko , 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, mpe@ellerman.id.au, 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, 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 v6] numa: make node_to_cpumask_map() NUMA_NO_NODE aware Message-ID: <20190924092551.GK2369@hirez.programming.kicks-ass.net> References: <1568724534-146242-1-git-send-email-linyunsheng@huawei.com> <20190923151519.GE2369@hirez.programming.kicks-ass.net> <20190923152856.GB17206@dhcp22.suse.cz> <20190923154852.GG2369@hirez.programming.kicks-ass.net> <20190923165235.GD17206@dhcp22.suse.cz> <20190923203410.GI2369@hirez.programming.kicks-ass.net> 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-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, Sep 24, 2019 at 09:29:50AM +0800, Yunsheng Lin wrote: > On 2019/9/24 4:34, Peter Zijlstra wrote: > > I'm saying the ACPI standard is wrong. Explain to me how it is > > physically possible to have a device without NUMA affinity in a NUMA > > system? > > > > 1) The fundamental interconnect is not uniform. > > 2) The device needs to actually be somewhere. > > > > From what I can see, NUMA_NO_NODE may make sense in the below case: > > 1) Theoretically, there would be a device that can access all the memory > uniformly and can be accessed by all cpus uniformly even in a NUMA system. > Suppose we have two nodes, and the device just sit in the middle of the > interconnect between the two nodes. > > Even we define a third node solely for the device, we may need to look at > the node distance to decide the device can be accessed uniformly. > > Or we can decide that the device can be accessed uniformly by setting > it's node to NUMA_NO_NODE. This is indeed a theoretical case; it doesn't scale. The moment you're adding multiple sockets or even board interconnects this all goes out the window. And in this case, forcing the device to either node is fine. > 2) For many virtual deivces, such as tun or loopback netdevice, they > are also accessed uniformly by all cpus. Not true; the virtual device will sit in memory local to some node. And as with physical devices, you probably want at least one (virtual) queue per node.