From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753762AbcHRCND (ORCPT ); Wed, 17 Aug 2016 22:13:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42378 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753542AbcHRCNC (ORCPT ); Wed, 17 Aug 2016 22:13:02 -0400 Reply-To: xlpang@redhat.com Subject: Re: [PATCH v7 2/2] Documentation: kdump: add description of enable multi-cpus support References: <1471485011-19035-1-git-send-email-zhouwj-fnst@cn.fujitsu.com> <1471485011-19035-3-git-send-email-zhouwj-fnst@cn.fujitsu.com> To: Zhou Wenjian , linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com, corbet@lwn.net, kexec@lists.infradead.org, linux-doc@vger.kernel.org From: Xunlei Pang Message-ID: <57B5199C.3080105@redhat.com> Date: Thu, 18 Aug 2016 10:12:44 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1471485011-19035-3-git-send-email-zhouwj-fnst@cn.fujitsu.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Thu, 18 Aug 2016 02:12:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/08/18 at 09:50, Zhou Wenjian wrote: > multi-cpu support is useful to improve the performance of kdump in > some cases. So add the description of enable multi-cpu support in > dump-capture kernel. > > Signed-off-by: Zhou Wenjian > Acked-by: Baoquan He > --- > Documentation/kdump/kdump.txt | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt > index 96da2b7..c93a6e0 100644 > --- a/Documentation/kdump/kdump.txt > +++ b/Documentation/kdump/kdump.txt > @@ -396,6 +396,13 @@ Notes on loading the 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. > > +* You should enable multi-cpu support in dump-capture kernel if you intend > + to use multi-thread programs with it, such as parallel dump feature of > + makedumpfile. Otherwise, the multi-thread program may have a great > + performance degradation. To enable multi-cpu support, you should bring up > + a SMP dump-capture kernel and specify maxcpus\nr_cpus, disable_cpu_apicid=[X] s/a SMP/an SMP/ For "maxcpus\nr_cpus", I think to use slash instead of backslash in Linux is better. Otherwise, looks good to me. Regards, Xunlei > + options while loading it. > + > * For s390x there are two kdump modes: If a ELF header is specified with > the elfcorehdr= kernel parameter, it is used by the kdump kernel as it > is done on all other architectures. If no elfcorehdr= kernel parameter is