Ooops!  the SL listserv didn't like my response, so I'm re-sending.  My 
apologies if you see a duplicate :-)

On 01/22/2013 03:12 AM, David Sommerseth wrote:
>
> Depending on the BSD flavour, of course, but FreeBSD 8.2+ and 9 have
> virtio support ...
>
>    <http://www.area536.com/projects/freebsd-as-a-kvm-guest-using-virtio/>
>    <http://people.freebsd.org/~kuriyama/virtio/>
>
> I believe there are some ongoing work for virtio support in both OpenBSD
> and NetBSD as well.  But that's also all I know.
>
> --
> kind regards,
>
> David Sommerseth
>

Many thanks for the info, David.  Very useful.

As it happens, I'm testing with multiple instances of m0n0wall, which is
based on FreeBSD v6.  I also have an instance of pfSense 2.0.2, which is
based on FreeBSD 8.1, so I guess I'm out of luck until m0n0wall moves to
v8.3 (in beta) and pfSense moves to v9 with rev.2.1.  That explains the
problem with Virtio.

Meanwhile, I tested an instance of Linux-based IPCop, which did use a
Virtio disk, but still had the problem of writes once per second.  It's
as if libvirtd does a sync every second, and there's some sort of data
being written each time.  Very strange.  I just discovered the
linux-kvm.org forum, so I probably should post my question there.

Chuck