What is normal range for CPU Wait time Per Dispatch on Hyper-V 2012

Question

Hello.
I am trying to troubleshoot some performance issues with an application that utilizes sql server, which runs in a Hyper-V Guest.
I have found that the ram, cpu, disk i/o all appear to be within normal range.
Before troubleshooting the sql end of things, I wanted to make make sure the vm isn't waiting for cpu time.
In Vmware, the metric for this is " CPU Ready". From what I can tell, the equivilant to this for Hyper-V on server 2012 is:
Hyper-V Hypervisor Virtual processor\CPU Wait time per dispatch.
I have fired this up and been monitoring it and found that the average is around 22,000, maximum 41,000.
The problem is, I have no idea if this is a normal or acceptable range. I can't seem to find any further information on actually interpreting this data, as to what is acceptable and what will cause performance issues etc..
Can anyone help enlighten me further on this?
Thanks

Answer 1

Hello.
I am trying to troubleshoot some performance issues with an application that utilizes sql server, which runs in a Hyper-V Guest.
I have found that the ram, cpu, disk i/o all appear to be within normal range.
Before troubleshooting the sql end of things, I wanted to make make sure the vm isn't waiting for cpu time.
In Vmware, the metric for this is " CPU Ready". From what I can tell, the equivilant to this for Hyper-V on server 2012 is:
Hyper-V Hypervisor Virtual processor\CPU Wait time per dispatch.
I have fired this up and been monitoring it and found that the average is around 22,000, maximum 41,000.
The problem is, I have no idea if this is a normal or acceptable range. I can't seem to find any further information on actually interpreting this data, as to what is acceptable and what will cause performance issues etc..
Can anyone help enlighten me further on this?
Thanks
Hi,
Hyper-V reports this metric is in nano seconds. So, your average is around 22-41 ms (milliseconds). This is GOOD.
Take this example:
This would be comparable to vCenter VM CPU Ready graph which displays VM CPU Ready time in milliseconds. 
Note #1: This measures each virtual core presented to an individual VM. This will be different if you're not using hyper-threading on the host 
Note #2:  This is scaled to a factor of 0.001, so that the scale on the left is in milliseconds - which is commonly confused with a percentage scale, which is is NOT.
Not to dismiss CPU issues, but generally the first place I look when troubleshooting SQL on a VM is storage access/speed/performance, regardless of what hypervisor is being used. I would verify best practices like putting databases on separate physical
storage that ends up on separate spindles on the storage back end, same for logs, same for temp db, same for temp log,...
Sam Boutros, Senior Consultant, Software Logic, KOP, PA http://superwidgets.wordpress.com (Please take a moment to Vote as Helpful and/or Mark as Answer, where applicable)