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Re: Xen2/NetBSD 3.1 DomU running slowly

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
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.


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