Awful FreeBSD 9 block IO performance in KVM

[Adrian Chadd]

On 19 July 2012 11:27, Richard Yao <ryao at gentoo.org> wrote:
> Dear Everyone,
>
> FreeBSD 9 has awful block IO performance in KVM. I have experienced it
> and others have experienced it. Someone posted slides to slideshare with
> benchmarks documenting it:
>
> http://www.slideshare.net/TakeshiHasegawa1/runningfreebsdonlinuxkvm
>
> Slides 13 and 20 are particular eye openers. Does anyone know what is wrong?

For those watching at home - this is bad performance _with_ the virtio
drivers themselves, not just with SCSI emulation.

Slide 17 is very telling - the operation latency is quite high.

Richard, are you able to easily test out things on FreeBSD-HEAD guest
in a Linux KVM? If so, some of the storage/block/GEOM driver people
may be able to step up and start offering some ideas.

Thanks,



Adrian