Xen project Mailing List

RE: [Xen-users] kernel-xen can not recognize more than 32 cores

To: mohammad mohammadi <m_mohammadi_dinani@xxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>

From: Jeff Sturm <jeff.sturm@xxxxxxxxxx>

Date: Fri, 4 Mar 2011 10:21:25 -0500

Cc:

Delivery-date: Fri, 04 Mar 2011 07:22:31 -0800

List-id: Xen user discussion <xen-users.lists.xensource.com>

Thread-index: AcvabjL9bsnHnSU6TEaARMLA2YerqQAEXLoQ

Thread-topic: [Xen-users] kernel-xen can not recognize more than 32 cores

We saw the same thing with our Dell R815 servers. I believe this limit is not due to the kernel, but to the hypervisor. Most 3.x releases of Xen had harcoded NR_CPUS to 32.

Run "xm dmesg" and see how many cores the hypervisor recognizes.

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of mohammad mohammadi
Sent: Friday, March 04, 2011 8:14 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] kernel-xen can not recognize more than 32 cores

Hi
I've installed xen hypervisor 3.0.3 on CentOS 5.5 from CentOS repository.
The hardware I use is a Tyan server with 48 cores( 4*12-cores processors ).
The original CentOS kernel 2.6.18.194 can recognize 48 cores perfectly, but when I switch to another kernel to use xen, the kernel recognize only 32 cores!
I tried to recompile the kernel by changing the maximum number of cpu in .config file, but nothing changed!
Can anyone help me?
Regards

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