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8 Replies Last post: Jan 8, 2007 12:40 PM by jsa

Dual core systems

Jul 13, 2006 9:40 AM

ghuda 1 posts since
Jul 13, 2006

Probably been answered but I couldn't find much on the search engine.
How does VMserver handle dual core systems w/SMP. If I setup a system with 2 DC Xeon 5140 processors, can my virtualized systems take advantage of all processors?
Thanks a ton for any help.

Re: Dual core systems Jul 13, 2006 10:01 AM

COS 602 posts since
Dec 12, 2005

On dual core systems, you can present one or both cores to the VM. This of course can be done through the GUI but you can also set CPU affinity in the .vmx file by adding these two lines...

Use only one processor...
processor0.use = "FALSE"
processor1.use = "TRUE"

Use both processors...
processor0.use = "TRUE"
processor1.use = "TRUE"

Re: Dual core systems Jul 13, 2006 10:11 AM

nick.couchman 4,583 posts since
Jan 13, 2006

VMware Server relies on the host O/S to schedule the jobs on the CPU's, so VMware Server will handle however many CPU's your host can handle. If you have 4 cores or more you can set up your guests to use VirtualSMP (multiple virtual CPU's) and have decent performance on those.

Re: Dual core systems Jul 13, 2006 10:41 AM

COS 602 posts since
Dec 12, 2005

I just realized I made a mistake. You have 4 cores (two dual core CPU's) so you should be able to assign affinity by the following...

Use only one core...
processor0.use = "FALSE"
processor1.use = "TRUE"
processor2.use = "FALSE"
processor3.use = "FALSE"

Use two cores...
processor0.use = "TRUE"
processor1.use = "TRUE"
processor2.use = "FALSE"
processor3.use = "FALSE"

Use all cores...
processor0.use = "TRUE"
processor1.use = "TRUE"
processor2.use = "TRUE"
processor3.use = "TRUE"

This is of course if you want to get granular on core assignments.
COS

Re: Dual core systems Jul 13, 2006 10:50 AM

in response to: COS

Peter_vm 9,056 posts since
Feb 1, 2006 Moderator

I just realized I made a mistake. You have 4 cores
(two dual core CPU's) so you should be able to assign
affinity by the following...

Those might still be able to perform hyperthreading, so there would be 8 logical CPUs in a physical host....

Use only one core...
processor0.use = "FALSE"
processor1.use = "TRUE"
processor2.use = "FALSE"
processor3.use = "FALSE"

Use two cores...
processor0.use = "TRUE"
processor1.use = "TRUE"
processor2.use = "FALSE"
processor3.use = "FALSE"

Use all cores...
processor0.use = "TRUE"
processor1.use = "TRUE"
processor2.use = "TRUE"
processor3.use = "TRUE"

This is of course if you want to get granular on core
assignments.
COS

Re: Dual core systems Jul 13, 2006 1:41 PM

in response to: COS

ksc 355 posts since
Sep 21, 2005 VMware

The default, of course, is "use all CPUs", effectively the same as saying "processorN.use=true" for each and every CPU.

This means each VCPU could run on each and every CPU that the host OS supports.

Re: Dual core systems Jan 8, 2007 10:59 AM

DanAndryszak 35 posts since
Mar 1, 2005

Is this information documented anywhere - other than this post?

Re: Dual core systems Jan 8, 2007 11:12 AM

in response to: DanAndryszak

Peter_vm 9,056 posts since
Feb 1, 2006 Moderator

Is this information documented anywhere - other than
this post?

Here?:
http://kb.vmware.com/kb/2039

Re: Dual core systems Jan 8, 2007 12:40 PM

in response to: Peter_vm

jsa 233 posts since
Nov 11, 2003

Does anyone know if Intel Core 2 Duo based machines also suffer from having Time Stamp Counters that get out of sync as mentioned in the referenced Kb article? http://kb.vmware.com/kb/2039

The reason I ask is that I had independently arrived at setting cpu affinity to vmware (linux host, windows guests) in vmware workstation (not server) as the only solution that would keep the VMware-vmx from jumping continuously from one cpu to the other, using 89 to 100% of both CPUs and still yielding unuseable performance.

This of course limits me to using 50% of the machines capability, which is problematic when I have multiple guests running.

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