[PATCH] kexec-kdump-howto:Add introduction of parallel dumping

[Pratyush Anand]

Hi Zhou,

Thanks for your work.

It seems its a V2. So please prefix with PATCH V2 and resend.

You can use:
git format-patch --subject-prefix="PATCH V2"

On 15/09/2015:10:34:14 AM, Zhou Wenjian wrote:
> Add descriptions of parallel dumping and how to use it.
> 
> Signed-off-by: Zhou Wenjian <zhouwj-fnst at cn.fujitsu.com>
> ---

And since its a single patch so, after you have done format-patch, please write
a change log here as it has been written in 
https://lists.fedoraproject.org/pipermail/kexec/2015-August/002271.html

>  kexec-kdump-howto.txt | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt
> index 05b497f..97a319c 100644
> --- a/kexec-kdump-howto.txt
> +++ b/kexec-kdump-howto.txt
> @@ -616,6 +616,38 @@ options are copied from /proc/cmdline. In general it is best to append
>  command line options using "KDUMP_COMMANDLINE_APPEND=" instead of replacing
>  the original command line completely.
>  
> +Parallel Dumping Operation
> +==========================
> +Kexec allows kdump using multiple cpus. So parallel feature can accelerate
> +dumping substantially, especially in executing compress and filter.
> +For example:
> +
> +	1."makedumpfile -c --num-threads [THREAD_NUM] /proc/vmcore dumpfile"
> +	2."makedumpfile -c /proc/vmcore dumpfile",
> +
> +	1 has better performance than 2, if THREAD_NUM is larger than two
> +	and the usable cpus number is larger than THREAD_NUM.
> +
> +Notes on how to use multiple cpus on a capture kernel on x86 system:
> +
> +Make sure that you are using a sufficiently new kernel version that supports

I remember Dave suggested to avoid "sufficiently new". So, if you do not agree
with some comment then please let that know, otherwise reviewer will assume that
you agreed.

> +disable_cpu_apicid kernel option as a capture kernel, which is needed to
> +avoid x86 specific hardware issue (*). The disable_cpu_apicid kernel option
> +is automatically appended by kdumpctl script and is ignored if the kernel
> +doesn't support it.
> +
> +You need to specify how many cpus to be used in a capture kernel by specifying
> +the number of cpus in nr_cpus kernel option in /etc/sysconfig/kdump. nr_cpus
> +is 1 at default.
> +
> +You should use necessary and suffcient amount of cpus on a capture kernel.

I still think that "number of cpus" would have been a better choice than "amount
of cpus".

Other than above two minor thing, patch looks fine to me.

~Pratyush