Re: Re: NUMA and SMP

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

* Petersson, Mats <Mats.Petersson@amd.com> [2007-03-20 11:33]:
> > -----Original Message-----
> > From: tgh [mailto:tianguanhua@ncic.ac.cn] 
> > Sent: 20 March 2007 13:50
> > To: Petersson, Mats
> > Cc: Emmanuel Ackaouy; Anthony Liguori; xen-devel; David 
> > Pilger; Ryan Harper
> > Subject: Re: [Xen-devel] Re: NUMA and SMP
> > 
> > Thank you for your reply
> > 
> > I see
> > and does xen support the numa-aware guestlinux now or in the future?
> 
> There is no support in current Xen for NUMA-awareness, and for the
> guest to understand NUMA-ness in the system, Xen must have sufficient
> understanding to forward the relevant information to the guest. 

As of Xen 3.0.4, Xen has support for detecting NUMA systems, parsing
SRAT tables which indicate how memory and cpu are split up between the
system NUMA nodes, support for allocating memory local to a particular
cpu.  To use NUMA, one must pass numa=on on the xen command line.

Xen still lacks a NUMA-aware scheduler, so one must be sure to pin vcpus
and keep your guest within a NUMA node.  This is done using the cpus=""
parameter in the guest config file.

Xen doesn't export any of the topology information is gleans from the
SRAT table at the moment.


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