Re: Re: NUMA and SMP

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

* Daniel Stodden <stodden@cs.tum.edu> [2007-03-22 10:03]:
> On Thu, 2007-03-22 at 08:02 -0500, Ryan Harper wrote:
> 
> > > > and for the paravirt xen-guest-linux do not support  numa-aware  now ,or 
> > > > does it  support  numa-aware  if CONFIG_NUMA choiced?
> > > 
> > > no. there is num-support in xen, as far as inspection of the memory
> > > topology and inclusion in the memory management is concerned. so
> > > basically, you can add the desired node number to get_free_pages().
> > 
> > There is NUMA support in Xen since 3.0.4 in the hypervisor, and we have
> > the capability to ensure a guest memory is local to the processors being
> > used.  The topology of the system is not exported to the guest so
> > CONFIG_NUMA in the guest kernel config will be of no value.
> 
> oops, that's more than i've noticed. thanks for the correction. so now
> it seems up to me to ask questions. :} i don't see that path taken along
> vcpu_migrate. where is it happening?

The credit scheduler is not NUMA aware.  So to ensure that the initial
allocation for the guest remains local, the domain uses a cpumask
(generated from cpus="" config file option)  to keep the scheduler from
migrating vcpus to off-node cpus.

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