CPU usage % and MHZ

[vSohill]

Hi,

For one of VM I have CPU usage 100% but in MHZ it is different. should it be direct line as well as the usage percentage ?

[dbalcaraz]

Hi,

When CPU is 100% it can be that MHz varies a bit.

Check CPU Usage: VMware vSphere 5.1

So for example it can be a 100% of CPU and the MHz can vary 300-500 MHz.

If you do the math, you should be able to match the values.

[vSohill]

Thanks dbalcaraz,

This chart for a VM. Does it mean the VM use 100 % of the physical CPU?

I thought this chart for how much the application or the guest OS utilizing the vCPU.

Am I right ?

[dbalcaraz]

It means that the vCPU that this VM is using is 100%, the pCPU doesn't need to be at 100%, just the resources assigned to the VM.

[Dave_the_Wave]

Without diving into NUMA and process affinity, if you are maxxing out on a 1 vCPU, generally it is being isolated on 1 pCPU's core.

Let's say you had a XenApp VM that was 4vCPU, and was being strained out when 100 users launch Chrome off it, if the host was also total 4 cores, then yes it is monopolizing the whole box.

[Dave_the_Wave]

I tested this with Sysinternal's CPUSTRES.EXE:

...on this VM with 1vCPU:

...and appears to be isolated on just 1 core (the X5670 is 6 cores with HT):

[dbalcaraz]

So, everything is right!

Which would be your doubt now?

[Dave_the_Wave]

I have never doubted anything I wrote.

I merely wanted to see for myself what I claimed was right.

You may have me confused with the Original Poster.

[dbalcaraz]

I see I did :smileywink: