Comments on: Use Hyperthreading in ESX or not?

By: tingshen

tingshen — Mon, 13 Apr 2009 16:10:24 +0000

So the answer is still back to the million dollar “consultant answer” – it depends!

In this case, seems like it’s application specific……

By: The VMguy

The VMguy — Mon, 05 Jan 2009 01:49:20 +0000

That is true and VMware upgraded the licensing so a single socket includes processors up to the newest 6-core Dunnington and Nehalem processors. You can read all the specifics here:
http://vmware.com/download/eula/multicore.html

Dave

By: Jason Boche

Jason Boche — Sun, 04 Jan 2009 22:14:30 +0000

@Justin Actually, better language would be that ESX is licensed by socket, not by cores or logical CPUs.

By: Justin

Justin — Wed, 31 Dec 2008 15:09:36 +0000

@Kurtis Lindemann Hyperthreading does not affect licensing in VMware. VMware is licensed by physical CPU, not by cores on a CPU or use of Hyperthreading.

By: Kurtis Lindemann

Kurtis Lindemann — Tue, 30 Dec 2008 21:05:13 +0000

Dave – how would hyperthreading effect licensing in VMware?

By: aharden

aharden — Tue, 30 Dec 2008 15:09:09 +0000

Great advice. I think the decision point to enable or disable HT on a 2P quad-core host is a lot safer than it was with similar single- and dual-core 2P hosts.

Another margin of safety is that ESX doesn’t start using the logical processors (the second set of registers made available by enabling HT) until it absolutely needs to, and even then, still favors physical processors when scheduling work. A good reference: http://communities.vmware.com/docs/DOC-5101.