Comments on: vSphere 4.1: Multicore Virtual CPUs

By: Parker Race

Parker Race — Mon, 08 Aug 2011 14:55:57 +0000

Thanks for the explanation.

By: jason

jason — Thu, 04 Aug 2011 19:15:04 +0000

2 vCPUs and 2 cores per socket should have resulted in 2 vCPUs (cores) in 1 socket which is what you saw. To use this feature correctly in vSphere 4, you provide the absolute number of cores (vCPUs) in the pull down box. The extra parameter works as a divider to tell the guest OS and its applications how many sockets the environment lives on. Here are a few examples:

Number of virtual processors: 1
cpuid.coresPerSocket: 1 (single core)
Number of cores OS/apps see: 1
Number of sockets OS/apps see: 1

Number of virtual processors: 2
cpuid.coresPerSocket: 1 (single core)
Number of cores OS/apps see: 2
Number of sockets OS/apps see: 2

Number of virtual processors: 2
cpuid.coresPerSocket: 2 (dual core)
Number of cores OS/apps see: 2
Number of sockets OS/apps see: 1

Number of virtual processors: 4
cpuid.coresPerSocket: 1 (single core)
Number of cores OS/apps see: 4
Number of sockets OS/apps see: 4

Number of virtual processors: 4
cpuid.coresPerSocket: 2 (dual core)
Number of cores OS/apps see: 4
Number of sockets OS/apps see: 2

Number of virtual processors: 4
cpuid.coresPerSocket: 4 (quad core)
Number of cores OS/apps see: 4
Number of sockets OS/apps see: 1

Number of virtual processors: 8
cpuid.coresPerSocket: 1 (single core)
Number of cores OS/apps see: 8
Number of sockets OS/apps see: 8

Number of virtual processors: 8
cpuid.coresPerSocket: 2 (dual core)
Number of cores OS/apps see: 8
Number of sockets OS/apps see: 4

Number of virtual processors: 8
cpuid.coresPerSocket: 4 (quad core)
Number of cores OS/apps see: 8
Number of sockets OS/apps see: 2

Hopefully you see the patterns here, the biggest one being “Number of virtual processors” will always equal “Number of cores OS/apps see”.
The calculation piece is the cores per socket configuration.

By: Parker Race

Parker Race — Thu, 04 Aug 2011 16:10:13 +0000

We are having weird results with this. I created a machine for Red Hat Linux 5.6. I assigned to vcpus and and 2 cores per socket. When the OS was installed it saw 1 cpu with 2 cores? We had to assigne 4 cpus with 2 cores per socket.

By: Collin C. MacMillan

Collin C. MacMillan — Mon, 08 Nov 2010 17:54:41 +0000

ugh, AMD 2400/6100… not 2300/6100

By: Collin C. MacMillan

Collin C. MacMillan — Mon, 08 Nov 2010 17:52:15 +0000

Actually, odd number of cores do work, despite the documentation:

http://solori.wordpress.com/2010/11/08/short-take-vsphere-multi-core-virtual-machines/

While functional, I suspect such configurations have limited support by VMware. However, in AMD 2300/6100 and Intel 5600 systems, the ability to match the virtual core count to the physical core count in NUMA systems could be very important deployment considerations.

By: jason

jason — Thu, 04 Nov 2010 19:52:17 +0000

@Jay
The VM is going to see cores and sockets. The VM will be able to take advantage of multiple cores per socket and realize all of the benefits that go along with that (namely licensing).

By: Jay Rogers

Jay Rogers — Thu, 04 Nov 2010 17:33:41 +0000

http://bit.ly/aUWglE is KB showing this. Should guest show all cores or just # of vCPU assigned the guest?

By: James

James — Wed, 03 Nov 2010 07:17:07 +0000

Is HA still available with multiple cores assigned?

By: Philippe

Philippe — Tue, 12 Oct 2010 14:24:03 +0000

Hi Jason,
Great feature but how can i configure a single virtual processor dual core?
I want to install MS SQL server on a virtual machine with one processor (cost of a licence) but dual core for performance.
My ESXi 4.1 host have a single processor 4 cores.

Thank you for any help.

By: jason

jason — Sun, 05 Sep 2010 18:24:25 +0000

Thanks for calling out the error Mike. I’ve updated the blog post with the correction.

By: Mike

Mike — Sat, 04 Sep 2010 09:52:45 +0000

Hate to be a nitpick, but 2^4=16, not 8. 2^3 however, is much closer to 8.

By: Bryan

Bryan — Mon, 30 Aug 2010 21:16:21 +0000

Hi Jason, this is good stuff. Do you know if there is an official VMware doc available that outlines the procedures on setting this up?

By: jason

jason — Mon, 02 Aug 2010 20:25:33 +0000

Enterprise Plus licensing is required for 8 vCPUs

By: Todd

Todd — Mon, 02 Aug 2010 20:11:20 +0000

Jason – Can you confirm that Enterprise *PLUS* licensing is required and not just Enterprise?

By: jason

jason — Fri, 30 Jul 2010 06:01:06 +0000

Yes I knew it but it wasn’t offically supported by VMware. In 4.1, VMware boasts this as a newly supported “feature”.