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[PATCH v10 0/3] Documentation: add description of enable multi-cpus support for kdump

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  [PATCH v10 0/3] Documentation: add description of enable multi-cpus support for kdump Baoquan He <bhe@redhat.com> - 2016-09-19 06:10 +0200
    [PATCH v10 3/3] Documentation: kdump: add description of enable multi-cpus support Baoquan He <bhe@redhat.com> - 2016-09-19 06:10 +0200
      Re: [PATCH v10 3/3] Documentation: kdump: add description of enable  multi-cpus support Baoquan He <bhe@redhat.com> - 2016-09-19 08:00 +0200

#1486118 — [PATCH v10 0/3] Documentation: add description of enable multi-cpus support for kdump

This is v10 post. In this patchset patch 1/3 is added to give more details
about nr_cpus and maxcpus in kernel-parameters.txt. This is suggested by
Jonathan since the description of them is unclear so that people can't see
what's the exact difference between them. Otherwise no big further change
for 2/3 and 3/3 which comprise the old post.

Please access below link to check the previous changelog.
https://lkml.org/lkml/2016/8/17/646

Baoquan He (1):
  docs: kernel-parameter : Improve the description of nr_cpus and
    maxcpus

Zhou Wenjian (2):
  Documentation: kdump: remind user of nr_cpus
  Documentation: kdump: add description of enable multi-cpus support

 Documentation/kdump/kdump.txt       |  9 +++++++++
 Documentation/kernel-parameters.txt | 20 +++++++++++++-------
 2 files changed, 22 insertions(+), 7 deletions(-)

-- 
2.5.5

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#1486120 — [PATCH v10 3/3] Documentation: kdump: add description of enable multi-cpus support

From: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>

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: Baoquan He <bhe@redhat.com>
---
 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

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#1486151 — Re: [PATCH v10 3/3] Documentation: kdump: add description of enable multi-cpus support

On 09/19/16 at 12:01pm, Baoquan He wrote:
> From: Zhou Wenjian <zhouwj-fnst@cn.fujitsu.com>
> 
> 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: Baoquan He <bhe@redhat.com>

Oh, sorry. My git config caused this Signed-off-by adding automatically.
Will resend. Nack this patchset.

> ---
>  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
> 

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