VMApache
Contributor
Contributor

CPUReady Extremely High on a VM

Hi Guys,

One of VM seems to be having CPU issue. VM has 2 CPUs and Windows OS installed on it. CPUReady Time is extremely high. VirtualCenter and esxtop command shows two different values. Although, VirtualCenter converting to Millseconds units where esxtop command shows in percent. I gone many posts here, somehow, I got confused!!! Can someone please take a look at screenshot and tell me that does CPU have any contention?

Thank you

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9 Replies
NTurnbull
Expert
Expert

Hi, how many other virtual machines are running on this host and how many vCPU's are they configured with?

Thanks,

Neil

Thanks, Neil
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VMApache
Contributor
Contributor

Thanks Neil,

Host is running with 11 VMs. 5 of VM is having 2vCPU and rest with 1vCPU. Host is 2xQuad Core processor.

Thanks you.

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TobiasKracht
Expert
Expert

Try to assign 1 vPCU to this VM.

StarWind Software R&D

StarWind Software R&D http://www.starwindsoftware.com
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VMApache
Contributor
Contributor

Thank you Tobias, We will try that. Before, we do that, can you please let me know is there CPU contention in that VM or not by looking at screenshots? I need to justify that before I get approval.

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NTurnbull
Expert
Expert

Hi, yes I would say that your running into CPU contention. It depends on the guest workloads and some other stats but if your 5 dual vCPU boxes are CPU intensive then your already going over your pCPU count. Take a look at this page for a great guide on how to interpret esxtop stats and the ways to find contetion http://communities.vmware.com/docs/DOC-9279.

As suggested by Tobias, yes I'd try allocating 1 vCPU per guest and only allocate more if it's required by that guest.

Thanks,

Neil

Thanks, Neil
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VMApache
Contributor
Contributor

Thank you both, I have another question with esxtop, what does mean that "idle" in the result? Is it overall usage of Host or VM?

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NTurnbull
Expert
Expert

From the link I post above:

  • "%IDLE"

The percentage of time the VCPU world is in idle loop. Note that %IDLE is included in %WAIT. Also note that %IDLE only makes sense to VCPU world. The other worlds do not have idle loops, so, %IDLE is zero for them.

I just re-read my last post, when I said that with just the 2 vCPU guest running your over your pCPU count, I meant only if they are trying to request cycles from the sheduler, not if they were idle

Thanks,

Neil

Thanks, Neil
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IB_IT
Expert
Expert

Thank you Tobias, We will try that. Before, we do that, can you please let me know is there CPU contention in that VM or not by looking at screenshots? I need to justify that before I get approval.

If you do go back to 1 vCPU, make sure u change the HAL on your Windows guest back to UNI proc as well. If you are using Win 2k3 SP2, it should be relatively simple.

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VMApache
Contributor
Contributor

Thank you all.

With ref to this link to calculate the vCenter performance statistics.

As of my screenshot, the Avearge is 17347 (One week data gathered)

17347/1800=0.9% (vCPU0)

26319/1800=2% (vCPU1)

As per VMware http://communities.vmware.com/docs/DOC-7390 interpreting the above value and checked with this document. As per that, there is no CPU contention.

Am I right with this calculation? Please correct me if I am wrong.

Thanks,

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