Awful FreeBSD 9 block IO performance in KVM

[Wojciech Puchar]

> da0: <QEMU QEMU HARDDISK 1.1.> Fixed Direct Access SCSI-5 device
> da0: 3.300MB/s transfers
> da0: Command Queueing enabled
> da0: 409600MB (838860800 512 byte sectors: 255H 63S/T 52216C)
>
> It does not explain why virtio is slow though, although I still need to
> test virtio against the latest code. I will do ivan's raw block test
> against virtio-blk, mainly because there is no point in doing it against
> a device whose transfers have been capped to 3.3MB/sec.
are you sure it is really capped?
i am not. just emulated sym device reports low speed.