From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756447AbcISEBe (ORCPT ); Mon, 19 Sep 2016 00:01:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51538 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751004AbcISEBX (ORCPT ); Mon, 19 Sep 2016 00:01:23 -0400 From: Baoquan He To: corbet@lwn.net, akpm@linux-foundation.org Cc: linux-doc@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, xlpang@redhat.com, dyoung@redhat.com, Zhou Wenjian , Baoquan He Subject: [PATCH v10 3/3] Documentation: kdump: add description of enable multi-cpus support Date: Mon, 19 Sep 2016 12:01:05 +0800 Message-Id: <1474257665-8838-4-git-send-email-bhe@redhat.com> In-Reply-To: <1474257665-8838-1-git-send-email-bhe@redhat.com> References: <1474257665-8838-1-git-send-email-bhe@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 19 Sep 2016 04:01:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhou Wenjian 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 Acked-by: Xunlei Pang Signed-off-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 f7ef340..b0eb27b 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 had better replace it with 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 an + SMP dump-capture kernel and specify maxcpus/nr_cpus, disable_cpu_apicid=[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 -- 2.5.5