Disable hyperthreading on a Virtual machine

[virtualvikram2]

Hi all.

We have a requirement, where we have to disable hyperthreading on a VM. Will there be any impact on a application runnning running on VM if we do it when VM is powered ON.

Regards,

Vikram.

[weinstein5]

Welcome to the Community - Hyperthreading is not set per VM but for the entire host - you will have to make the change in the systems BIOS which will require a reboot - but I have to ask why do you want to do this VMware best practice is to have Hyperthreading enabled for you hosts -

[virtualvikram2]

Hi,

Thanks for replying.

I am sorry, we want to disable hyperthreaded core sharing in the virtual machine>> properties> resources. Will there be any impact if we set hyperthreaded core sharing to none for a virtual machine.

Thanks in Advance.

Vikram.

[weinstein5]

Not on the VM itself but their could be an impact on other VMs because when you set HT Sharing to none what you will be doing is causing the Virtual CPUs of the virtual machine should not share cores with each other or with virtual CPUs from other virtual machines. That is, each
virtual CPU from this virtual machine should always get a whole core to itself,  with the other logical CPU on that core being placed into the halted state thus reducing the number available LCPU that a VMs VCPU can use and this can cause other VMs to rait for CPU cycles -

you can find more information here on the different settings - vSphere Documentation Center

[virtualvikram2]

Thanks alot for answer.