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

Zhou Wenjian
2016-07-29T03:24:35Z

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@cn.fujitsu.com>
---
Documentation/kdump/kdump.txt | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 9a77247..155a63c 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -394,6 +394,12 @@ Notes on loading the dump-capture kernel:
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify nr_cpus=1 option while loading dump-capture kernel.

+* 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 nr_cpus=[X] and
+ disable_cpu_apic=[Y] 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