From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from [59.151.112.132] (helo=heian.cn.fujitsu.com) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bbdqI-0006D8-GO for kexec@lists.infradead.org; Mon, 22 Aug 2016 01:15:59 +0000 Message-ID: <57BA51E0.1070902@cn.fujitsu.com> Date: Mon, 22 Aug 2016 09:14:08 +0800 From: =?UTF-8?B?Ilpob3UsIFdlbmppYW4v5ZGo5paH5YmRIg==?= MIME-Version: 1.0 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> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Jonathan Corbet Cc: bhe@redhat.com, linux-doc@vger.kernel.org, xlpang@redhat.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, joe@perches.com, akpm@linux-foundation.org, dyoung@redhat.com, vgoyal@redhat.com T24gMDgvMTkvMjAxNiAxMTo1NyBQTSwgSm9uYXRoYW4gQ29yYmV0IHdyb3RlOgo+IE9uIEZyaSwg MTkgQXVnIDIwMTYgMDg6MzM6MjEgKzA4MDAKPiAiWmhvdSwgV2Vuamlhbi/lkajmlofliZEiIDx6 aG91d2otZm5zdEBjbi5mdWppdHN1LmNvbT4gd3JvdGU6Cj4KPj4gSSB3YXMgYWxzbyBjb25mdXNl ZCBieSBtYXhjcHVzIGFuZCBucl9jcHVzIGJlZm9yZSB3cml0aW5nIHRoaXMgcGF0Y2guCj4+IEkg dGhpbmsgaXQgaXMgYSBnb29kIGNob2ljZSB0byBkZXNjcmliZSBpdCBpbiBrZXJuZWwtcGFyYW1l dGVycy50eHQuCj4+Cj4+IFRoZW4sIG9ubHkgdHdvIHRoaW5ncyBuZWVkIHRvIGJlIGRvbmUgSSB0 aGluay4KPj4gT25lIGlzIG1vdmUgdGhlIGFib3ZlIGRlc2NyaXB0aW9uIHRvIG1heGNwdXM9IGlu IGtlcm5lbC1wYXJhbWV0ZXJzLnR4dC4KPj4gQW5kIHRoZSBvdGhlciBpcyByZXBsYWNlIG1heGNw dXMgd2l0aCBtYXhjcHVzL25yX2NwdXMgaW4ga2R1bXAudHh0Lgo+Pgo+PiBIb3cgZG8geW91IHRo aW5rPwo+Cj4gVGhhdCBpcyBub3QgcXVpdGUgd2hhdCBJIGhhZCBpbiBtaW5kLCBzb3JyeS4gIFdo YXQgSSB3b3VsZCByZWFsbHkgbGlrZSB0bwo+IHNlZSBpbiBrZXJuZWwtcGFyYW1ldGVycy50eHQg aXMgYW4gZXhwbGFuYXRpb24gb2YgaG93IHRob3NlIHR3byBwYXJhbWV0ZXJzCj4gZGlmZmVyIC0g d2hhdCBkbyB0aGV5IGRvIGRpZmZlcmVudGx5IGFuZCBob3cgc2hvdWxkIGEgdXNlciBjaG9vc2Ug b25lIG92ZXIKPiB0aGUgb3RoZXI/ICBXaGF0IHdlIGhhdmUgbm93IG9mZmVycyBubyBndWlkYW5j ZSBpbiB0aGF0IG1hdHRlci4KPgoKSSB0aG91Z2h0IGFib3V0IGl0LiBJIHRoaW5rIHVzZXIgbWF5 IG5vdCBuZWVkIHRoaXMuCldoYXQgdXNlciByZWFsbHkgd2FudCB0byBrbm93IGlzIGhvdyB0byBj aG9vc2UuCkFuZCBpdCBpcyBhbHNvIG5vdCBhIGhhcmQgd29yay4gSWYgbnJfY3B1cyBpcyBub3Qg c3VwcG9ydGVkIGJ5IHRoZSBBUkNILCB1c2UgbWF4Y3B1cy4KT3RoZXJ3aXNlLCBucl9jcHVzLiBU aGUgcmVhc29uIHdoeSBtYXhjcHVzIHN0aWxsIGV4aXN0cyBpcyBucl9jcHVzIGNhbid0IGJlIHN1 cHBvcnRlZApieSBzb21lIEFSQ0hlcy4KCkkgdGhpbmsgaXQgbWF5IGJlIHdoeSB0aGUgYXV0aG9y IGRpZG4ndCB3cml0ZSB0b28gbXVjaCBkZXNjcmlwdGlvbiBvZiBpdC4KCj4gSSBzdXNwZWN0IHRo YXQgbWF5IGJlIGEgYml0IG1vcmUgdGhhbiB5b3UgaGFkIHNpZ25lZCB1cCB0byBkby4gIEFzIGFu Cj4gaW50ZXJtZWRpYXRlIHN0ZXAsIGhvdyBhYm91dCB0aGlzOiByYXRoZXIgdGhhbiB0YWNraW5n IG9uIHRob3NlIGxpbmVzIGluCj4ga2R1bXAudHh0LCByZXdyaXRlIHRoYXQgcGFyYWdyYXBoIHRv IHNpbXBseSBzYXkgd2hhdCB0aGUgcmVhZGVyIHNob3VsZAo+IHVzZS4gIElmIG5yX2NwdXMgaXMg Z29vZCBmb3IgZXZlcnlib2R5LCBqdXN0IHNheSB0aGF0LCBidXQgeW91ciBwcmV2aW91cwo+IHBh dGNoIHN1Z2dlc3RzIHRoYXQgdGhlIHNpdHVhdGlvbiBpc24ndCBxdWl0ZSB0aGF0IHNpbXBsZT8K PgoKQWN0dWFsbHksIGlmIG5yX2NwdXMgYWx3YXlzIHVzYWJsZSwgdGhlcmUgd29uJ3QgYmUgdGhl c2UgZGlzY3Vzc2lvbnMuCgoKLS0gClRoYW5rcwpaaG91CgoKCl9fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fCmtleGVjIG1haWxpbmcgbGlzdAprZXhlY0BsaXN0 cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGlu Zm8va2V4ZWMK 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