From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756433AbcHCCGh (ORCPT ); Tue, 2 Aug 2016 22:06:37 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:10385 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752199AbcHCCG2 (ORCPT ); Tue, 2 Aug 2016 22:06:28 -0400 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="9455894" Message-ID: <57A15156.3060507@cn.fujitsu.com> Date: Wed, 3 Aug 2016 10:05:10 +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: Baoquan He CC: , , , Subject: Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel References: <1470185952-23477-1-git-send-email-zhouwj-fnst@cn.fujitsu.com> <1470185952-23477-2-git-send-email-zhouwj-fnst@cn.fujitsu.com> <20160803015818.GB2465@x1.redhat.com> In-Reply-To: <20160803015818.GB2465@x1.redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-yoursite-MailScanner-ID: 45D144295942.A819F 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 08/03/2016 09:58 AM, Baoquan He wrote: > On 08/03/16 at 08:59am, Zhou Wenjian wrote: >> SMP dump-capture kernel is useful to improve the performance of kdump in >> some cases. So add the description of bringing up SMP dump-capture kernel. >> >> Signed-off-by: Zhou Wenjian >> --- >> Documentation/kdump/kdump.txt | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt >> index 4aa194e..948b42d 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, we should replace it by nr_cpus to >> save memory if supported by the current ARCH, such as x86. >> >> +* We should bring up a SMP dump-capture kernel if we intend to use > > Well, here about SMP dump-capture kernel do you mean kdump kernel with > multi-cpu? If I understand it correctly, it's still SMP kdump kernel > though nr_cpus=1 is specified. > Actually, I haven't know the detail about it. I wrote the sentence almost based on the original description: * 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. >> + multi-threads programs with it, such as parallel dump feature of >> + makedumpfile. Otherwise, the multi-threads program may have a great >> + performance degradation. To bring up a SMP dump-capture kernel, we >> + should specify maxcpus\nr_cpus and disable_cpu_apic=[X] 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 >> -- >> 1.8.3.1 >> >> >> >> >> _______________________________________________ >> kexec mailing list >> kexec@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/kexec > > -- Thanks Zhou