From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754313AbcHSA5O (ORCPT ); Thu, 18 Aug 2016 20:57:14 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:38212 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754239AbcHSA5L (ORCPT ); Thu, 18 Aug 2016 20:57:11 -0400 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="10059371" Message-ID: <57B653D1.8060106@cn.fujitsu.com> Date: Fri, 19 Aug 2016 08:33:21 +0800 From: =?UTF-8?B?Ilpob3UsIFdlbmppYW4v5ZGo5paH5YmRIg==?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Jonathan Corbet CC: , , , , , , , , Subject: Re: [PATCH v9 1/2] Documentation: kdump: remind user of nr_cpus References: <1471489907-27737-1-git-send-email-zhouwj-fnst@cn.fujitsu.com> <1471489907-27737-2-git-send-email-zhouwj-fnst@cn.fujitsu.com> <20160818111854.362bb972@lwn.net> In-Reply-To: <20160818111854.362bb972@lwn.net> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-yoursite-MailScanner-ID: 0430B42BC500.AE01F X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: zhouwj-fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jonathan, Thanks for your reply. On 08/19/2016 01:18 AM, Jonathan Corbet wrote: > On Thu, 18 Aug 2016 11:11:46 +0800 > Zhou Wenjian wrote: > > Thank you for working to improve the documentation! > >> * We generally don' have to bring up a SMP kernel just to capture the >> dump. Hence generally it is useful either to build a UP dump-capture >> kernel or specify maxcpus=1 option while loading dump-capture kernel. >> + Note, though maxcpus always works, you should replace it by nr_cpus to >> + save memory if supported by the current ARCH, such as x86. > > So, IMHO, this seems like the wrong place for this. I've just spent a bit > of time staring at kernel-parameters.txt, and there is no way for a > clueless user like me to know what the difference is between maxcpus= and > nr_cpus= would be. A far better patch would be to update the > documentation there to make that clear. Any chance you would be willing > to do that? > > Then, rather than tacking an "ignore what you just read" note into > kdump.txt, it could maybe be rewritten to simply say what users should do? > I was also confused by maxcpus and nr_cpus before writing this patch. I think it is a good choice to describe it in kernel-parameters.txt. Then, only two things need to be done I think. One is move the above description to maxcpus= in kernel-parameters.txt. And the other is replace maxcpus with maxcpus/nr_cpus in kdump.txt. How do you think? -- Thanks Zhou