Poor CPU performance of virtual machine

[Michael_987]

Hello

we have a an esxi 5 server. Theres only one virtual machine running. it's A SBS 2008. The server is running slow, it seems to depend on the CPU (XEON 5502 2 cores with hyperthreading) utlisation. The windows task manager shows  60%-75% Utilisation most of the time and often 100%.

But the vmware (vsphere) performance chart shows only 20% to maximum 60%, although the CPU ressource reservation of the vitrual machine is high and unlimited. Is it possible, to give the virutal machine more CPU power?

Thank you very much for your help!

MIchael

[LennieDH]

Maybe stating the obvious...but did have you already checked in vSphere Client, select host -> configuration -> power management -> properties -> High performance ?

Regards,

Paolo

[Michael_987]

Hello Paolo

often the obvious is correct 🙂

but I cant find any powermanagment under configuration. It is not the same as in the picture of my first question (ressources...)?

Michael

[LennieDH]

Hello,

yes, it should be in your "Konfiguration" tab, then on left side of screen you should have a "Power Management" link.

Here's a screen from my environment:

Hope this helps,

Regards,

Paolo

[Michael_987]

Oh yes thank you for the screenshot.

my configuration is:

technology: enhanced intel speed step

active policy: not supported

there is nothing to configure, Properties is grey

MIChael

[LennieDH]

Hello,

so that is not its fault since power management is disabled on your host.

This is greyed out because either hardware does not support power managment or power management by OS is disabled in BIOS (http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=101820...)

Sorry I've no further ideas on what could resolve your issue, hope someone else could give you some useful hints.

Regards,

Paolo

[gregsn]

Hello Michael,

Just to clarify, how may physical CPU cores are on the host system?  You mention that you have two cores, hyperthreaded, and it seems as though you have four vCPUs allocated to the guest machince.  If you only have two physical CPU cores, this will probably cause excessively high CPU Ready times, which will cause high CPU usage on the guest and low CPU usage on the host (because the host is waiting for four CPUs to available before scheduling them to the guest, which would be hard for it to do with only two cores + hyperthreading).

If you have only two physical CPU cores on the host, I recommend not assigning more than one, two at the most, to the guest, otherwise you'll going to run into CPU scheduling issues (high CPU Ready times).  Have you tried running the guest machine with a single vCPU assigned?

Greg

[Michael_987]

Hello Greg

thanks for the suggestions.

I think I explained it wrong. There are two sockets on the board. Each with a XEOn and 2 cores. So overall 4 logic CPUs

If I change the CPU count Is there any problem with the server 2008 system?

BTW Why does vmware state "hyper threading is not available"?

MIChael

[gregsn · Accepted solution]

It seems as though your processor does not have hyperthreading.  As per Intel's specifications http://ark.intel.com/products/37092/Intel-Xeon-Processor-E5502-4M-Cache-1_86-GHz-4_80-GTs-Intel-QPI

Having all four cores assigned to a single VM is probably causing the CPU performance issues.  Have you checked the CPU Read values?  If you are seeing more than 1000msec per vCPU, you can expect performance degredation.

Chaning the VM from four to one or two vCPUs shouldn't be a problem unless you have some software running which is consuming a lot of CPU time.  I've run SBS2011 on a single vCPU without any problems.