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

["Zhou, Wenjian/周文剑"]

Hello,

Thanks for reviewing. I will resend the v2 patch.

On 09/16/2015 02:20 PM, Pratyush Anand wrote:
> 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"
>

I see.

> 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
>

I see.

>>   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.
>

Sorry, I haven't noticed that.

>> +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".
>

I see.

-- 
Thanks
Zhou

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