CPU ready - right values??

[rocker77]

Hello,

I have question about ready time in monitoring CPU. I have SQL server with 2 vCPU a ready time is between 15 and 30ms (max 50ms). Which value tell me ... add another vCPUs?? When I set only 1 vCPU a got nearly same values.

Thank you for support!!

Best regards, Roman.

[dpomeroy]

When you say you went from 2 vCPU to 1 vCPU did you also change the HAL in the VM?

Also ready times are a result of overall system utilization and how resources are configured for each VM.

Don Pomeroy

VMTN Communities User Moderator

[OlivierTremolie]

Hi,

How many Physical CPU have you got on your ESX ? How many VM is running on it and is there many VM with 2VCPU ?

Olivier

[rocker77]

dpomeroy: Yes, I change HAL. We have W2K3 server. But what values are good results??

OlivierTremolieres: I have one pCPU (Quad core) and totaly three VMs. Terminal server, linux and Windows 2003 SBS (Exchange, SQL). Only SBS use vSMP (two vCPU). I know, that I can´t use more than one VM with two vCPU and I can´t use four vCPU now (limitation of SBS and ESX). Customer plan another VMs and we will buy next quad core CPU.

[OlivierTremolie]

Well, at the most-basic level high CPU Ready values can be caused by simply running multiple VMs on the same ESX server, and the ESX server is "running out" of CPU cycles to allocate to the VMs. Or, if you are using a VM running applications that require a great deal of processing, this can also cause the VM to have a high CPU ready value.

I am not sure there are really any hard and fast rules regarding CPU ready value. The value of 5% was from a VMware pdf, so it is something to consider, but that isn't really an absolute value. If you have a server that is rarely used, and users won't notice if the server is being heavily loaded, then 5% CPU ready may not be a problem. If the VM is running an often-used, critical application, then users may notice if the VM is "waiting" for a processor 5% of the time it is running. Like a lot of things, "it depends".

I'm not sure that a VM running at higher than 5% CPU could cause other VMs to be slow-performing. However, when a VM is running at a high value of CPU ready, this is an indication that the ESX host is lacking CPU resources, and the other VMs will likely encountering the same issue.

Olivier

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[ejward]

I am not sure there are really any hard and fast rules regarding CPU ready value. The value of 5% was from a VMware pdf, so it is something to consider, but that isn't really an absolute value. If you have a server that is rarely used, and users won't notice if the server is being heavily loaded, then 5% CPU ready may not be a problem. If the VM is running an often-used, critical application, then users may notice if the VM is "waiting" for a processor 5% of the time it is running. Like a lot of things, "it depends".

What do you mean by 5%? 5% of what? CPU Ready is expressed in Miliseconds. I have a SQL VM that has an average CPU Ready of 300 miliseconds. I don't know if that's good or bad. Do I add another CPU?