CPU Ready

[logiccomm]

Hi team,

Regarding CPU Ready and the table below:

   <5% - generally no problems

   5-10% - monitor and resolve if application impacted

   10%+ - critical and resolve immediately

What I'd like to know is if these values apply "per vCore", or "per VM".

As an example, if I look at a VM's "Readiness" inside vCenter. It has 6 vCores. Each core is averaging 2% (however %RDY in ESXTOP is giving me 12% which is the summation of each core). Am I safe (2%) or should I be deeply worried (12%)?

Should I be taking the value provided by in ESXTOP labelled "%RDY", and dividing this by the number of vCores to get the true CPU ready value, which I can then use in the table above? Or do I simply look at the Readiness value for each core to determine whether it is healthy?

Thanks.

[jmbrav0]

You don't have to do any summation.

This is the definition of CPU Ready:

%RDY – (Ready) % of time a vCPU was ready to be scheduled on a physical processor but could not be due to contention.  You do not want this above 10% and should look into anything above 5%.

If your %RDY value is <5% in the ESXTOP, don't worry about it.

If your %RDY value is >10% maybe your VM has more vCores that it needs.

[ThompsG]

Hi there,

Recommendation is per vCore so 12% across 6 cores is not a problem. %CSTP (co-stop) is the counter you should look at to see if the VM has more cores allocated than is needed and the VM is actually penalizing itself due to this.

To see the behavior in ESXTOP, from the CPU view, press "e" and then the world ID. This will expand the counters for this VM and from here you will see that the VM %RDY matches the sum of the vCores.

Kind regards.