Re: KVM performance

[Fabian Deutsch <fabian.deutsch-Mmb7MZpHnFY@public.gmane.org>]

Hey,

> Hi,
> 
> I did some testing of KVM on my woodcrest machine.  And I found that
> building a 2.6.19 kernel with identical configuration takes 845 sec on a
> guest and 210 sec on the host.  So the compile is about 4X slower on the
> guest :(

I wasn't able to compile some vanilla kernels, but i did two loops on
the host and guest.

First, with nearly no hd read/writes.
# time (for I in $(seq 1 100000) ; do echo $I > /dev/null ; done)
host:	3.7s	100%
guest:	4.1s	110%

And a second one with hd read/writes (might have a look at strace of
date, tells you that date open/closes a lot of files):
# time (for I in $(seq 1 1000) ; do date > /dev/null ; done)
host:	1s	100%
guest:	14s	1400%

i don't really know how much those tests say, but:
It seems as if the hd access is the bottleneck :)

fabian


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