zeebahi
Enthusiast
Enthusiast

VM CPU utilization

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Hi everyone,

Please consider the following example:

VM1- --ESXi_1


Above ESXi-1 has single VM1.

ESXi-1 has following CPU resource:

ESXI1-CPU-VM1.PNG

We assign VM1 single CPU:

VM1-CPU.PNG

Based on the above, what is max CPU resources VM1 can use? Should it not be more than  2.59 GHZ because ESXI has two logical CPU of 2.59GHZ each and VM1 is using single vCPU which is scheduled on a single  Logical CPU on ESxi-1 at any given time.

Thanks and have a good day!!

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daphnissov
Immortal
Immortal

If you have one vCPU assigned to this VM and the underlying pCPU is of frequency 2.59 GHz, assuming hyperthreading is in use here you may be able to use slightly more from a frequency perspective. If you look at the total resources consumed by this VM at the ESXi host level, it will be a little higher than that because ESXi consumes some of its own resources in order to run VMs. This is known as overhead.

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daphnissov
Immortal
Immortal

If you have one vCPU assigned to this VM and the underlying pCPU is of frequency 2.59 GHz, assuming hyperthreading is in use here you may be able to use slightly more from a frequency perspective. If you look at the total resources consumed by this VM at the ESXi host level, it will be a little higher than that because ESXi consumes some of its own resources in order to run VMs. This is known as overhead.

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zeebahi
Enthusiast
Enthusiast

Thanks for you response.

I just started learning  ESXi , basically this how i visualize :

vCPU--I/O -Scheduler--I/O--pCPU

Based on above, vCPU  can not exceed pCPU  (  ignoring  slight ESXi's overhead required for VM)

Am i on the right track ?

Thanks and have a good day!!

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daphnissov
Immortal
Immortal

If you are new to ESXi and vSphere, I would actually recommend that you do some reading of the Mastering vSphere series. This is well as other books are some great resources to help newcomers learn the technology.

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zeebahi
Enthusiast
Enthusiast

Thanks  for the guidance.  I just ordered it.

Have a nice day!!

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