From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1blpm2-0001fK-Kd for kexec@lists.infradead.org; Mon, 19 Sep 2016 04:01:43 +0000 From: 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> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: corbet@lwn.net, akpm@linux-foundation.org Cc: Baoquan He , linux-doc@vger.kernel.org, kexec@lists.infradead.org, Zhou Wenjian , xlpang@redhat.com, linux-kernel@vger.kernel.org, dyoung@redhat.com 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 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec