linux-kernel - Re: [PATCH v7 2/2] Documentation: kdump: add description of enable multi-cpus support

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Message-ID: <57B5199C.3080105@redhat.com>
Date:	Thu, 18 Aug 2016 10:12:44 +0800
From:	Xunlei Pang <xpang@...hat.com>
To:	Zhou Wenjian <zhouwj-fnst@...fujitsu.com>,
	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, dyoung@...hat.com, bhe@...hat.com,
	vgoyal@...hat.com, corbet@....net, kexec@...ts.infradead.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v7 2/2] Documentation: kdump: add description of enable
 multi-cpus support

On 2016/08/18 at 09:50, Zhou Wenjian wrote:
> 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@...fujitsu.com>
> Acked-by: Baoquan He <bhe@...hat.com>
> ---
>  Documentation/kdump/kdump.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
> index 96da2b7..c93a6e0 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 should replace it by 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
> +  a SMP dump-capture kernel and specify maxcpus\nr_cpus, disable_cpu_apicid=[X]

s/a SMP/an SMP/
For "maxcpus\nr_cpus", I think to use slash instead of backslash in Linux is better.

Otherwise, looks good to me.

Regards,
Xunlei

> +  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