Virtual Center showing different cpu usage than VM does

[colinr]

We just recently migrated about 75 2 processor phsyical machines using P2V to VM's using 2 vcpu's. These windows 2000 servers are spread out over 8 bl45p's with 4 dual core and 16gb of memory each. We are using VC2.

Now, we are seeing an issue were some of the VM's are showing different cpu useage average than VC show. Some of the VM's are within about 5% of VC. Is there a setting that can be changed to correct this difference? Should VC be watched over the perfmon off the VM?

any help/ideas would be appreciated.

Message was edited by:

colinr

[TCronin]

There are many, many posts and articles on this. The CPU numbers in the VM using perfmon or task manager are almost never correct. In a very small nutshell this has to do with the scheduling of the vcpus among the physical CPU's. ESX can't just disconnect the cpu so the time that the OS thinks it has the CPU is diffrent than the time that it actually is processing on a CPU. That's very simplistec of course, there are other factors invloved also.

You can try vmperfmon from www.run-virtual.com if you have to have something available in the machine for end users.

You also might see better performance with 1 VCPU and a uniprocessor HAL on those guest. Out of slighty over 1000 machines running in production I only have 2 that have more than one processor. Most apps are not truly multi-threaded and the overhead need to schedule 2 vcpus is greater than any return on processing power.

[colinr]

thanks