How much processor on virtual machine?

[TRAINING]

Hi,

I have on my server 1 Xeon Quad CPU.

How many cpu (1 or 2) is better to indicate for each virtual machine? If I indicated only 1 CPU, the virtual machine use only one CPU instead 4 parallel cpu bulted on Xeon Quad?

Thanks in advance

[AWo]

I would give as least CPU's as possible (depends on application requirement which is running in the guest).

Maximum number is 1/2 of the number of cores.

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[TRAINING]

The selection of core to use (1 or 2 of the 4 avaible) is automatic?

If indicated only one processor on the guest the operating system is able to automatically distribute the load on the various core?

[AWo]

The selection of core to use (1 or 2 of the 4 avaible) is automatic?

Yes.

If indicated only one processor on the guest the operating system is able to automatically distribute the load on the various core?

Not the operating system but VMware will schedule the load of the guest over all cores.

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[TRAINING]

It is useless to give 2 cpu instead of one on a guest if VMWare manages the load on the 4 core. correct?

[AWo · Accepted solution]

It is useless to give 2 cpu instead of one on a guest if VMWare manages the load on the 4 core. correct?

No, I wouldn't say so. The guest can benefit from more processors. But you need a guest OS and an application which is able to use and benefit from more than one processor. It is the same story as if you would install the stuff on a physical machine.VMware itself has no benefit from adding more than one processor to the guest.

It is only the guest which may have an advantage and therefore it depends on its OS and application. Remember that the guest runs natively on the CPU(s) which is (are) scheduled for the guest.

In other words, a single processor guest OS with an single processor application wouldn't run faster.

Remember also that VMware offers SMP (symmetric multiprocessing), that means that as many cores has to be free for scheduling to the guest at a given moment as you have assigned to the guest (if you have assigned two virtual CPU's to the guest VMware has to find two free CPU cores to give them to the guest at a given time).

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