vCenter CPU performance tab vs Windows Task manager

[online111]

Hi everyone,

I can see differences between performance monitoring Windows Task manager VS Vcenter realtime CPU monitoring. Please check attached snapshots.

When Windows task manager shows %100 cpu usage, vcenter shows it %25 cpu

Vmtools and VM hardware levels are all up to date.

Do you have and idea why?

Thanks...

[admin]

This should answer your question

http://blog.logicmonitor.com/2013/02/25/a-tale-of-two-metrics-windows-cpu-or-vcenter-vm-cpu/

Thanks,
Avinash

[online111]

Hello there,

According to this blog what I understand is, ESXi is sharing CPU with other VMs, so that this graph wont show same cpu usage as windows task manager.. Is that right?

I have 2 questions here.

1. I have assigned dedicated cpu reservation for the VM, and it still shows %25 cpu usage on vcenter, and %100 on Windows nothing changed.

2. I have moved this VM to another cluster, test there and this time vcenter CPU usage is same with task manager.

So I dont understand why is that?

Both clusters are fully utilized, there are lots of VMs running.

Thanks

[admin]

yes , Guest CPU and Host CPU may not be same always depending on the vCPU assigned. So if your having difference  between two  hosts then it could be a different situation,

are you using any resource pools..??

[online111]

I dont use resource pools.

I have 3 different ESXi clusters all running on ESX 5.1

Moved this VM between those clusters and only in one cluster CPU graph is not matching with Windows task manager.

I will give more details tomorrow.

Thanks in advance.

[online111]

I have moved same VM across clusters. They are all running ESX5.1 hosts.

Assigned 2-4-8 vCPUs and checked if there is any differences nothing changed.

CPU reservation, did not affect anything.

Cluster1: VM CPU performance not matching Windows task manager

Cluster2: Matching

Cluster3: Matching

Cluster1 is the least loaded cluster I have. Other clusters are %30 loaded, cluster1 is around %5 load.

I cannot understand the logic behind this. If VMware Vcenter will not show the real cpu consumption of the VM, why do they have cpu performance tab showing up there?

Can you guys check VM cpu performance tab vs Task manager and comment your results?

Thanks

[homerzzz]

I checked several of my VMs and the stats match.

When you move your VM to cluster2 or cluster3, does the vcenter performance chart show 100% to match the VM, or does the VM drop to 25% to match the vcenter performance chart? Is this the only VM displaying this behavior? Are all three of your clusters configured exactly the same?

[online111]

Hi,

Configurations are all identical on clusters

When I move from cluster 2 to cluster 3 VM cpu usage is matching.

Only cluster1 showing 25% and this applies to all VMs under cluster1. If a VM running 100% cpu, vcenter performance shows it as 25% or 26%

All 7 hosts showing same figure under cluster1

I have 301 VMs running under cluster1 (not matching)

277 VMs under cluster2 (matching)

431 VMs under cluster3 (matching)

71 VMs under cluster4 (matching)

[sahancelikag]

Answer is this:

virtual CPU usage = usagemhz ÷ (number of virtual CPUs × core frequency in mhz)

VMWARE: vCenter CPU performance tab vs Windows Task manager usage

[abugeja]

Sorry to dig up an old thread but had a further question. Does anyone else out there have SCOM to monitor their virtual machine environment and if so what volume metrics do you use?

[abugeja]

anyone?