[RFC] makedumpfile, crash: LZO compression support

[Atsushi Kumagai]

> > Hello Hatayama-san,
> > 
> > Thank you for your work.
> > 
> >> Performance Comparison:
> >> 
> >>   Sample Data
> >> 
> >>     Ideally, I must have measured the performance for many enough
> >>     vmcores generated from machines that was actually running, but now
> >>     I don't have enough sample vmcores, I couldn't do so. So this
> >>     comparison doesn't answer question on I/O time improvement. This
> >>     is TODO for now.
> > 
> > I'll measure the performance for actual vmcores by makedumpfile.
> > Please wait for a while.

I measured the performance of makedumpfile for some vmcores.
Please see below.


Sample Data
  
  To simulate a working server, I captured VMCOREs while almost all pages 
  were alloceted and filled with random data. (See attached file "fill_random.c")

  I captured the VMCOREs of 5GB, 7.5GB and 10GB in the same condition.

How to measure

  I measured the total execution time and the size of output file.

  $ time makedumpfile --message-level 16 [-c|-l| ] vmcore dumpfile

Result

    See attached file "result.txt".


This time, lzo's compression was the quickest, and lzo's compression ratio is
almost the same(only a bit worse) as zlib's.
It seems good, and I will merge the patch set into the makedumpfile.

What is your opinion, Dave?


Thanks.
KUMAGAI, Atsushi

> 
> That's very helpful. Thanks in advance.
> 
> But of course I'm also still looking for alternative way.
> 
> Thanks.
> HATAYAMA, Daisuke
> 
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