makedumpfile 1.5.4 + kernel 3.11-rc2+ 4TB tests

[Jingbai Ma]

Hi,

I have run some tests with makedumpfile 1.5.4 and upstream kernel 
3.11-rc2+ on a machine with 4TB memory, here is testing results:

Test environment:
Machine: HP ProLiant DL980 G7 with 4TB RAM.
CPU: Intel(R) Xeon(R) CPU E7- 2860  @ 2.27GHz (8 sockets, 10 cores)
(Only 1 CPU was enabled the 2nd kernel)
Kernel: 3.11.0-rc2+ (at patch b3a3a9c441e2c8f6b6760de9331023a7906a4ac6)
crashkernel=384MB
vmcore size: 4.0TB
Dump file size: 15GB
All measured time from debug message of makedumpfile.
As a comparison, I also have tested makedumpfile 1.5.3.

(all time in seconds)
                     Excluding pages   Copy data   Total
makedumpfile 1.5.3          468         1182       1650
makedumpfile 1.5.4           93          518        611


So it seems there is a great performance improvement by the mmap mechanism.

--
Thanks,
Jingbai Ma
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