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

[Baoquan He]

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>

> ---
>  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
> 
> 
>