makedumpfile parallel dumping test

[Jingbai Ma]

Hi all,

I have done some experiments on parallel kernel dumping. I would like to 
share the test result with you. Hope it helps.

Test environment:
Machine: HP ProLiant DL980 G7 with 4TB RAM.
CPU: Intel(R) Xeon(R) CPU E7- 2860  @ 2.27GHz (8 sockets, 10 cores) (4 
CPU were enabled the 2nd kernel by nr_cpus=4)
Kernel 3.9.0-rc7
kexec-tools 2.0.4
makedumpfile v1.5.3 with lzo library
crashkernel=4096M (I have tested with 2048M but failed with OOM on 3 or 
4 parallels dumping in cyclic mode)

I didn't get a real multipath storage device, so I just put dump files 
on 4 different disks via 3 HP Smart Array controllers. (mounted on /0, 
/1, /2 and /3 in the capture kernel)

Measured time like this (for example: lzo compression, non-cyclic, 4 
parallels):
time makedumpfile -l -non-cyclic --split --message-level 23 -d 31 
/proc/vmcore /0/vmcore_0 /1/vmcore_1 /2/vmcore_2 /3/vmcore_3

I run several tests with different option, parallels from 1 to 4, and 
combined with zlib and lzo compression.

Test result:
-----------------------------------------------------------------
|               |Parallels 1|Parallels 2|Parallels 3|Parallels 4|
-----------------------------------------------------------------
|zlib cyclic    | 42m25.321s|  34m0.168s| 29m44.908s| 28m50.387s|
-----------------------------------------------------------------
|zlib non-cyclic|  42m7.842s| 28m28.275s| 23m25.750s|  21m6.476s|
-----------------------------------------------------------------
|lzo cyclic     | 23m40.010s| 18m19.932s| 21m47.903s| 22m47.605s|
-----------------------------------------------------------------
|lzo non-cyclic | 20m45.749s| 16m42.045s| 15m41.070s| 15m18.605s|
-----------------------------------------------------------------


-- 
Thanks,
Jingbai Ma