From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753736AbcHVBPh (ORCPT ); Sun, 21 Aug 2016 21:15:37 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:57375 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753093AbcHVBPf (ORCPT ); Sun, 21 Aug 2016 21:15:35 -0400 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="10129352" Message-ID: <57BA51E0.1070902@cn.fujitsu.com> Date: Mon, 22 Aug 2016 09:14:08 +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> <57B653D1.8060106@cn.fujitsu.com> <20160819095740.1cccc073@lwn.net> In-Reply-To: <20160819095740.1cccc073@lwn.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-yoursite-MailScanner-ID: DF184430CD45.AB257 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 On 08/19/2016 11:57 PM, Jonathan Corbet wrote: > On Fri, 19 Aug 2016 08:33:21 +0800 > "Zhou, Wenjian/周文剑" wrote: > >> 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? > > That is not quite what I had in mind, sorry. What I would really like to > see in kernel-parameters.txt is an explanation of how those two parameters > differ - what do they do differently and how should a user choose one over > the other? What we have now offers no guidance in that matter. > I thought about it. I think user may not need this. What user really want to know is how to choose. And it is also not a hard work. If nr_cpus is not supported by the ARCH, use maxcpus. Otherwise, nr_cpus. The reason why maxcpus still exists is nr_cpus can't be supported by some ARCHes. I think it may be why the author didn't write too much description of it. > I suspect that may be a bit more than you had signed up to do. As an > intermediate step, how about this: rather than tacking on those lines in > kdump.txt, rewrite that paragraph to simply say what the reader should > use. If nr_cpus is good for everybody, just say that, but your previous > patch suggests that the situation isn't quite that simple? > Actually, if nr_cpus always usable, there won't be these discussions. -- Thanks Zhou