Re: IO on guest is 20 times slower than host

Avi Kivity
2009-03-25T16:35:35Z

Kurt Yoder wrote:
>>
>> I get 141 MB/s on the same test (it only copies to memory anyway).
>> Is your VM under memory pressure?
>
> I don't think so. The host has 128 GB of memory, and even the
> pre-emptive kernel caching doesn't come close to filling it:
>
> me@host:~$ free
> total used free shared buffers cached
> Mem: 132043960 1742480 130301480 0 84628 826040
> -/+ buffers/cache: 831812 131212148
> Swap: 1048568 0 1048568
>
> My /tmp should be physical disk in both cases. To be thorough, I also
> ran the test while writing the output file to /, and got the same
> results (5.7 MB/s on guest, 144 MB/s on host).

Your guest is only assigned 256MB though.

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