On 06/26/2015 03:07 PM, Atsushi Kumagai wrote:
Hello Zhou,
>Hello Atsushi Kumagai,
>
>I test this patch set in several machines and the following is the benchmark.
Thanks for your report, it looks good as before.
I also did simple test on kernel 3.19 on a 5GB Virtual Machine,
but I can't get such good result as below:
/ # time makedumpfile -c --num-threads 0 /proc/vmcore /mnt/dumpfile
Copying data : [100.0 %] /
The dumpfile is saved to /mnt/dumpfile.
makedumpfile Completed.
real 0m 44.40s
user 0m 43.62s
sys 0m 0.69s
/ #
/ # time makedumpfile -c --num-threads 4 /proc/vmcore /mnt/dumpfile
Copying data : [100.0 %] -
Copying data : [100.0 %] /
The dumpfile is saved to /mnt/dumpfile.
makedumpfile Completed.
real 5m 29.54s
user 6m 8.18s
sys 16m 33.25s
/ #
There is a big performance degradation.
Do you have any ideas why this happens ?
Does your Virtual Machine have more than 2 processors?
If so, check the value:nr_cpus in KDUMP_COMMANDLINE_APPEND of
/etc/sysconfig/kdump.
It should be also set to the number larger than 2.
To "--num-threads 4", the most suitable number of processors is 5.
--
Thanks
Zhou Wenjian
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