Contributor

## 2 x Quad Core 3.0Ghz Xeon Processors = How Many Total GHz?

Here is a stupid question for you that has more to do with Xeon technology than VI, but anyhow...

If I have 2 x Quad Core 3.0GHz Xeon processors in a server, what is the total available CPU that can be allocated in GHz? Some people are saying 6GHz (i.e. 2 x 3.0GHz) other people are saying 24GHz (i.e. 2 x 4 x 3.0GHz). We need an authoritative answer on this question to put an end to the debate once and for all, and so that we can go back to doing real work...

1 Solution

Accepted Solutions
Immortal

No. Total amount of GHz is 223 = 12 GHz - SC reservation (by default 240MHz). You can distribute all this gigahertzes, but since 1 physical core has a clock of 3 GHz you can't give more than 3 GHz to 1vCPU VM and more than 6GHz to 2vCPU VM.

EMCCAe, MCITP: SA+VA, VCP 3/4/5, VMware vExpert http://blog.vadmin.ru
6 Replies
Immortal

the total amount is 24 GHz but to a single virtual CPU is 3 GHz since a vCPU will be scheduled to a single core -

Contributor

So what does that translate into as far as total allocatable CPU? 21GHz?

Contributor

Okay, I made a mistake with the original question, sorry. In reality, we have 2 x Dual Core 3.0GHz Xeon Processors. The actual debate is that we have 9GHz worth of CPU for provisioning purposes to safely allocate to Virtual Machines, not 12GHz, due to vCPU scheduling. Is there any truth to this assertion?

Immortal

No. Total amount of GHz is 223 = 12 GHz - SC reservation (by default 240MHz). You can distribute all this gigahertzes, but since 1 physical core has a clock of 3 GHz you can't give more than 3 GHz to 1vCPU VM and more than 6GHz to 2vCPU VM.

EMCCAe, MCITP: SA+VA, VCP 3/4/5, VMware vExpert http://blog.vadmin.ru
Immortal

Anton hit the nail on the head - it all boils down to what the vCPU is scheduled to and it is a single core -