From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f70.google.com (mail-oi0-f70.google.com [209.85.218.70]) by kanga.kvack.org (Postfix) with ESMTP id 9DC796B025F for ; Fri, 29 Sep 2017 02:48:58 -0400 (EDT) Received: by mail-oi0-f70.google.com with SMTP id h9so263197oia.11 for ; Thu, 28 Sep 2017 23:48:58 -0700 (PDT) Received: from szxga04-in.huawei.com (szxga04-in.huawei.com. [45.249.212.190]) by mx.google.com with ESMTPS id r189si1730912oif.85.2017.09.28.23.48.53 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 28 Sep 2017 23:48:57 -0700 (PDT) Subject: Re: [PATCH 1/1] mm: only dispaly online cpus of the numa node 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> From: "Leizhen (ThunderTown)" Message-ID: <59CDEC59.8040102@huawei.com> Date: Fri, 29 Sep 2017 14:46:49 +0800 MIME-Version: 1.0 In-Reply-To: <20170828131328.GM17097@dhcp22.suse.cz> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Will Deacon Cc: linux-kernel , linux-api , Greg Kroah-Hartman , linux-mm , Zefan Li , Xinwei Hu , Tianhong Ding , Hanjun Guo , Catalin Marinas 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org