linux-kernel - [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel

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Message-ID: <1470185952-23477-2-git-send-email-zhouwj-fnst@cn.fujitsu.com>
Date:	Wed, 3 Aug 2016 08:59:12 +0800
From:	Zhou Wenjian <zhouwj-fnst@...fujitsu.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<kexec@...ts.infradead.org>, <bhe@...hat.com>, <dyoung@...hat.com>,
	<d.hatayama@...fujitsu.com>
Subject: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel

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 <zhouwj-fnst@...fujitsu.com>
---
 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
+  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