Documentation: kdump: Add description of enable multi-cpus support
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 <zhouwj-fnst@cn.fujitsu.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Xunlei Pang <xpang@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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 @@
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