linux-kernel - Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing up SMP dump-capture kernel

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Message-ID: <20160803015818.GB2465@x1.redhat.com>
Date:	Wed, 3 Aug 2016 09:58:18 +0800
From:	Baoquan He <bhe@...hat.com>
To:	Zhou Wenjian <zhouwj-fnst@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org, dyoung@...hat.com,
	d.hatayama@...fujitsu.com, kexec@...ts.infradead.org
Subject: Re: [PATCH v3 2/2] Documentation: kdump: add description of bringing
 up SMP dump-capture kernel

On 08/03/16 at 08:59am, Zhou Wenjian wrote:
> 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@...fujitsu.com>
> ---
>  Documentation/kdump/kdump.txt | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
> index 4aa194e..948b42d 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, we should replace it by nr_cpus to
>    save memory if supported by the current ARCH, such as x86. 
>  
> +* We should bring up a SMP dump-capture kernel if we intend to use

Well, here about SMP dump-capture kernel do you mean kdump kernel with
multi-cpu? If I understand it correctly, it's still SMP kdump kernel
though nr_cpus=1 is specified.

> +  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 maxcpus\nr_cpus and disable_cpu_apic=[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
> -- 
> 1.8.3.1
> 
> 
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

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