linux-kernel - Re: [PATCH v10 3/3] Documentation: kdump: add description of enable multi-cpus support

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Date:   Mon, 19 Sep 2016 13:52:57 +0800
From:   Baoquan He <bhe@...hat.com>
To:     corbet@....net, akpm@...ux-foundation.org
Cc:     linux-doc@...r.kernel.org, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, xlpang@...hat.com, dyoung@...hat.com,
        Zhou Wenjian <zhouwj-fnst@...fujitsu.com>
Subject: 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@...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@...fujitsu.com>
> Acked-by: Baoquan He <bhe@...hat.com>
> Acked-by: Xunlei Pang <xpang@...hat.com>
> Signed-off-by: Baoquan He <bhe@...hat.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
>