Re: Setting dom0-cpus to 0 doesn't use all cpus asdocumented

[Ryan Harper <ryanh@us.ibm.com>]

* Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> [2006-05-09 10:07]:
> > The comments for dom0-cpus in the xend-config.sxp file 
> > indicate that setting this value to 0 in an SMP system will 
> > cause dom0 to use all the available CPUs. However, it appears 
> > as if setting this value to 0 does not change the number of 
> > CPUs at all.
> > 
> > I'm running SLES10 Beta 11 and xen-unstable changeset 9960 on 
> > a Unisys ES7000 with 32 CPUs and 32GB memory. In 
> > xend-config.sxp, dom0-cpus is set to 0. When xen dom0 boots, 
> > it is using all 32 procs (as reported by 'grep processor 
> > /proc/cpuinfo | wc -l').
> > 
> > If I edit the xend-config.sxp file, change the value of 
> > dom0-cpus to 1, and restart xend, dom0 correctly uses 1 CPUs. 
> > If I then change dom0-cpus to 0 and restart xend, dom0 still 
> > uses 1 cpu. The only way to have dom0 use 32 cpus again is to 
> > either set the value of dom0-cpus to 32, or reboot xen.
> > 
> > Has anyone else seen this behavior?
> 
> You can just use the normal xm commands to vary the number of CPUs.
> Restarting xend is a rather brutal way of trying to achieve the same
> thing...

Is it worth keeping dom0-cpus then?


-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@us.ibm.com