Xen2/NetBSD 3.1 DomU running slowly

[Stephen Borrill <netbsd%precedence.co.uk@localhost>]

Every now and then I get reports of a customer's DomU running slowly and, 
sure enough, when I connect it takes ages to login. However, it's running 
at 100% idle and the other DomU on the same box is fine. A reboot of the 
DomU fixes it. When it happened today, I saw the following on the Dom0 
console (which is running quickly and responsively):

xen_shm_map: ENOMEM
xen_shm_map: ENOMEM1
xvif3.0: can't map packet page

The first two are debugging, I believe, but the third looks suspicious...

The kernels are 3.1_STABLE from 20th Nov 2006. Have there been pullups 
that fix this, i.e. should I be updating? I'm not in a position to upgrade 
to NetBSD 4.0/Xen3 at the moment.

--
Stephen