Calculation of virtual resources

central-processing-unitvcpuvmware-esxi

I virtualized a server using VMware ESXi. My virtual machine has 8 vCPU, while the real processor is an Intel Xeon E5-2620 v3 (6 core) @ 2,4 GHz. In order to estimate virtual resources needed for running that virtual machine, is it correct the following calculation?
Total amount of GHz = # of vCPU * clock CPU = 8 * 2,4 = 19,2 GHz

Thanks in advance.

Andrea

Best Answer

The VMware vSphere documentation (https://pubs.vmware.com/vsphere-60/index.jsp#com.vmware.vsphere.monitoring.doc/GUID-FB4C372B-49AC-4A0F-8573-D8E23241570A.html), about CPU charts said:

Amount of CPU actively used by the host, resource pool, or virtual machine in the cluster.
■ Counter: usagemhz
■ Stats Type: Rate
■ Unit: MegaHertz (MHz)

So, it seems in the chart representing CPU usage of virtual machine, it gives informations about consumption; therefore, as I said in the previous comment, in that chart, a 5% CPU usage corresponds to 961 MHz, meaning that 100% corresponds to 19,2 GHz.
On the other hand, from the same type of chart applied to the host I can see a 6,96% usage corresponds to 1000 MHz used, which means 100% corresponds to 14,4 GHz. And 14,4 GHz is also the result of the calculation:
Total amount of GHz = # of CPU * clock CPU = 6 * 2,4 GHz= 14,4 GHz, where 6 is the number of cores of the real processor.
I think the answer is in the CPU usage charts.

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