[PATCH] makedumpfile: Add more descriptions of multi-threads feature

[Atsushi Kumagai]

Hello, 

>On 07/29/16 at 11:34am, Zhou Wenjian wrote:
>> It will have a bad performance if the threads number is larger than
>> the usable cpu number. So we should remind user of it.
>>
>> Signed-off-by: Zhou Wenjian <zhouwj-fnst at cn.fujitsu.com>
>
>It makes sense to tell people who use option "-num-threads".
>Ack it.
>
>Acked-by: Baoquan He <bhe at redhat.com>

Looks good to me, I'll merge this into v1.6.1.

Thanks,
Atsushi Kumagai

>> ---
>>  makedumpfile.8 | 2 ++
>>  print_info.c   | 2 ++
>>  2 files changed, 4 insertions(+)
>>
>> diff --git a/makedumpfile.8 b/makedumpfile.8
>> index 3b6f7e2..f74abea 100644
>> --- a/makedumpfile.8
>> +++ b/makedumpfile.8
>> @@ -376,6 +376,8 @@ the kdump\-compressed format.
>>  \fB\-\-num\-threads\fR \fITHREADNUM\fR
>>  Using multiple threads to read and compress data of each page in parallel.
>>  And it will reduces time for saving \fIDUMPFILE\fR.
>> +Note that if the usable cpu number is less than the thread number, it may
>> +lead to great performance degradation.
>>  This feature only supports creating \fIDUMPFILE\fR in kdump\-comressed
>>  format from \fIVMCORE\fR in kdump\-compressed format or elf format.
>>  .br
>> diff --git a/print_info.c b/print_info.c
>> index 1a9f70c..2fbfb12 100644
>> --- a/print_info.c
>> +++ b/print_info.c
>> @@ -200,6 +200,8 @@ print_usage(void)
>>  	MSG("  [--num-threads THREADNUM]:\n");
>>  	MSG("      Using multiple threads to read and compress data of each page in parallel.\n");
>>  	MSG("      And it will reduces time for saving DUMPFILE.\n");
>> +	MSG("      Note that if the usable cpu number is less than the thread number, it may\n");
>> +	MSG("      lead to great performance degradation.\n");
>>  	MSG("      This feature only supports creating DUMPFILE in kdump-comressed format from\n");
>>  	MSG("      VMCORE in kdump-compressed format or elf format.\n");
>>  	MSG("\n");
>> --
>> 1.8.3.1
>>
>>
>>