We are trying to determine the pros and cons of allotting different number of CPUs to VMs (VMware). We would like to see how the VMware kernel is dividing up the total number of cores/threads and determine the best architecture for our specific software configuration needs. Is anyone aware of how to look at IRQ interrupts within the ESXi kernel?
IRQ Interrupts ESXi
irqvmware-esxi
Best Answer
I was unsure if VMware was emulating the CPU when I asked this question. Assuming it did we could look at the physical hosts interrupts to determine the best way to divide up our resources. However, there is no emulation that takes place at all. As it was explained, consider a virtual system board with a hole, the guest OS simply looks through the hole and sees one of the cores in the host server. This takes the pressure of VMware to change theCPU emulation software each time a vendor introduced new instruction sets. The other reasoning is it adds too much overhead. The VMkernel schedules simultaneously CPU cycles for multi-CPU VMs. When the VM requests for cycles the request goes into a queue for the host to process and the host waits until there are at least two cores or hyperthreads to schedule that VM.