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zeebahi
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VM Ready time in Over provisioned CPU case

Hi every body!!

Consider the following examples:

Example #1

Single ESXi with  4 Logical CPU. Single VM with single VCPU.

Is one specific logical CPU on ESXi dedicated for VCPU of VM above?

Or it is not dedicated, ESXi will use any one of free logical CPUs for VCPU above?

Example#2

On VCenter, when  VM is selected, and if we see Performance>Advance>CPU, we see " READY" which tells us the time VM is waiting for physical CPU's attention.

Keeping the above in mind, we should see "READY" time for VM only in  over provisioned logical CPU cases. In cases, where we do not have over provisioned logical CPUs  we should not see "READY" time right?

Thanks and have a good weekend!!

v

1 Solution

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a_p_
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Example #1

You can actually dedicate/pin vCPUs to a VM, in which case the scheduler will not use other vCPUs. However, that's something that should be considered very well, and isn't usually required. With default settings, the scheduler does a good job, and schedules CPU slices on any available vCPUs.

Example#2

CPU Ready time in such cases should be low, but not necessarily zero.

Think of it like driving on a highway. Even if there's no traffic jam, you may need to slow down do to other drivers.

André

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a_p_
Leadership
Leadership
Jump to solution

Example #1

You can actually dedicate/pin vCPUs to a VM, in which case the scheduler will not use other vCPUs. However, that's something that should be considered very well, and isn't usually required. With default settings, the scheduler does a good job, and schedules CPU slices on any available vCPUs.

Example#2

CPU Ready time in such cases should be low, but not necessarily zero.

Think of it like driving on a highway. Even if there's no traffic jam, you may need to slow down do to other drivers.

André