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

To: Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: NUMA and SMP
From: tgh <tianguanhua@xxxxxxxxxx>
Date: Wed, 28 Mar 2007 09:50:16 +0800
Cc: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, Ryan Harper <ryanh@xxxxxxxxxx>, Daniel Stodden <stodden@xxxxxxxxxx>
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xen does not support numa-aware guest linux, is it right?
and there are memory-hotplug.c and migration.c in the linux2.6.20, does it means that linux could support the hotplug memory or not ? if it could ,does linux have to be numa-aware to support memory hotplug or a smp linux could support memory hotplug?

I am confused about it

could you help me
Thanks in advance

Petersson, Mats 写道:
-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ryan Harper
Sent: 23 March 2007 14:43
To: tgh
Cc: Xen Developers; Daniel Stodden
Subject: Re: [Xen-devel] Re: NUMA and SMP

* tgh <tianguanhua@xxxxxxxxxx> [2007-03-23 00:48]:
how many nodes in the numa with adm64 does xen support at present?
in xen/include/asm-x86/numa.h:
#define NODE_SHIFT=6

#in xen/include/xen/numa.h:
#define MAX_NUMNODES = (1 << NODE_SHIFT);

which works out to 64 nodes.  I don't know if anyone has tested more
than an 8 node system.

Of course, if we're talking AMD64 systems, if a NODE is a socket, the
currently available architecture supports 8 NODES, so there's plenty of
space to grow such a system. I think there's plans to grow this, but I
doubt that the limit above will be reached anytime soon.

Even if a node is a core within a CPU, the current limit of 8 sockets
will limit the number of cores in a system to 32 cores when the
quad-core processors become available. So still sufficient to support
any current architecture.

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

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