I got this from VM Support:
When an operating system is idle, it enters its idle loop. If the idle loop executes a halt instruction on the CPU, CPU resources are released. In the case of a physical machine, this release typically results in lower power consumption. In the case of a virtual machine, the release results in idle CPU resources which can then be retasked for use by other active virtual machines.
On some Windows, the OS spins in the idle loop for a longer time before executing the halt instruction. When the system is virtualized, this results in increased physical CPU utilization even when there is no substantial activity in the guest operating system.
you can try to override this idle loop handler's behavior on a per-virtual machine basis by adding or modifying the following virtual machine configuration (.vmx) file option and assigning a value for n between 100 and 4000:
monitor.idleLoopSpinUS = "n"
Values outside of this range are unlikely to result in resource utilization improvements. In comparison with the default value:
- A lower value means that the virtual machine is halted more quickly and uses fewer physical CPU cycles when idle.
- A higher value means that the virtual machine is allowed to spin longer before being halted.
The advantage of allowing the virtual machine to spin longer in the idle loop prior to being halted by the VMkernel is that the transition of a virtual machine to active state (executing code other than the idle loop) occurs far quicker from idle state than from halted state. As a result, lowering the value can reduce guest operating system performance and responsiveness in certain circumstances, such as with workloads that have time-sensitive, I/O-intensive, or interactive requirements, which cycle often between idle and active.
I would suggest to try 100, 4000 and -1 (in order to let the OS choose the best value).
In order to set up the monitor.idleLoopSpinUS parameter you can edit the vmx file while the VM is powered off or:
Shut down the virtual machine
Click Edit Settings on the Virtual Machine Summary Page to access the virtual machine Settings Page.
Click the Options tab and choose Advanced.
Click Configuration Parameters. The Configuration Parameter window appears.
Click Add Row.
Enter monitor.idleLoopSpinUS as Name and -1 , for example as Value. Click OK.
Click OK.
If after trying the 3 options still doesn't fix the issue:, I will need to get the logs of the ESX with support data on them:
cd /tmp
vm-support -s
Please, let me know if it works.
