Re: Xen2/NetBSD 3.1 DomU running slowly

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

On Tue, 3 Jul 2007, Manuel Bouyer wrote:
> > > On Thu, May 31, 2007 at 09:24:51AM +0100, Stephen Borrill wrote:
> > > > 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.
> > >
> > > You may have an usage that requires more VM space for inter-domains
> > > communications than is currenly allocated. You can try increasing
> > > XENSHM_NPAGES
> > > in sys/arch/xen/i386/xen_shm_machdep.c
> > Would doubling it be a fair increase?
>
> Yes, in fact it really depends on how much domUs will do a full ring of I/Os
> at the same time (or how much interfaces in a single domU)

Single interface in each domU. 2 domUs per box. The domU in question is 
just running Apache (and some perl cgis) and ipfilter. It serves about 
50GB of data per month (i.e. not too heavy load). I'd have thought this 
was pretty standard usage.

--
Stephen