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RE: [Xen-devel] Re: NUMA and SMP

To: "Ryan Harper" <ryanh@xxxxxxxxxx>
Subject: RE: [Xen-devel] Re: NUMA and SMP
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Tue, 20 Mar 2007 17:47:47 +0100
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, tgh <tianguanhua@xxxxxxxxxx>
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Thread-topic: [Xen-devel] Re: NUMA and SMP
 

> -----Original Message-----
> From: Ryan Harper [mailto:ryanh@xxxxxxxxxx] 
> Sent: 20 March 2007 16:46
> To: Petersson, Mats
> Cc: tgh; xen-devel
> Subject: Re: [Xen-devel] Re: NUMA and SMP
> 
> * Petersson, Mats <Mats.Petersson@xxxxxxx> [2007-03-20 11:33]:
> > > -----Original Message-----
> > > From: tgh [mailto:tianguanhua@xxxxxxxxxx] 
> > > 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.

Thanks for the update - I must have missed that it went in. 

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



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