From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751830AbdI2GrL (ORCPT ); Fri, 29 Sep 2017 02:47:11 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:7470 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbdI2GrJ (ORCPT ); Fri, 29 Sep 2017 02:47:09 -0400 Subject: Re: [PATCH 1/1] mm: only dispaly online cpus of the numa node To: Michal Hocko , Will Deacon References: <1497962608-12756-1-git-send-email-thunder.leizhen@huawei.com> <20170824083225.GA5943@dhcp22.suse.cz> <20170825173433.GB26878@arm.com> <20170828131328.GM17097@dhcp22.suse.cz> CC: linux-kernel , linux-api , Greg Kroah-Hartman , linux-mm , Zefan Li , Xinwei Hu , Tianhong Ding , Hanjun Guo , Catalin Marinas From: "Leizhen (ThunderTown)" Message-ID: <59CDEC59.8040102@huawei.com> Date: Fri, 29 Sep 2017 14:46:49 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20170828131328.GM17097@dhcp22.suse.cz> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020206.59CDEC67.0127,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: b5f1cdc886463560c57cd1142f71aede Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017/8/28 21:13, Michal Hocko wrote: > On Fri 25-08-17 18:34:33, Will Deacon wrote: >> On Thu, Aug 24, 2017 at 10:32:26AM +0200, Michal Hocko wrote: >>> It seems this has slipped through cracks. Let's CC arm64 guys >>> >>> On Tue 20-06-17 20:43:28, Zhen Lei wrote: >>>> When I executed numactl -H(which read /sys/devices/system/node/nodeX/cpumap >>>> and display cpumask_of_node for each node), but I got different result on >>>> X86 and arm64. For each numa node, the former only displayed online CPUs, >>>> and the latter displayed all possible CPUs. Unfortunately, both Linux >>>> documentation and numactl manual have not described it clear. >>>> >>>> I sent a mail to ask for help, and Michal Hocko replied >>>> that he preferred to print online cpus because it doesn't really make much >>>> sense to bind anything on offline nodes. >>> >>> Yes printing offline CPUs is just confusing and more so when the >>> behavior is not consistent over architectures. I believe that x86 >>> behavior is the more appropriate one because it is more logical to dump >>> the NUMA topology and use it for affinity setting than adding one >>> additional step to check the cpu state to achieve the same. >>> >>> It is true that the online/offline state might change at any time so the >>> above might be tricky on its own but if we should at least make the >>> behavior consistent. >>> >>>> Signed-off-by: Zhen Lei >>> >>> Acked-by: Michal Hocko >> >> The concept looks find to me, but shouldn't we use cpumask_var_t and >> alloc/free_cpumask_var? > > This will be safer but both callers of node_read_cpumap are shallow > stack so I am not sure a stack is a limiting factor here. > > Zhen Lei, would you care to update that part please? > Sure, I will send v2 immediately. I'm so sorry that missed this email until someone told me. -- Thanks! BestRegards