Virtualization: Should I assign CPU’s or Cores
TL:DR Cores Cores Cores (but no more than pCPU count)
When creating a new virtual machine in VMware ESXi or VMware Workstation, it asks you how may processor cores you wish to set and gives you the option to set both ‘Number of processors‘ and ‘Number of cores per processor‘.
Most places online (looking at you Stack Overflow) said that only ‘Total processor cores‘ matters. I was curious as to how true that was and decided to run some tests myself.
The results are as follows
| CPU’s | Cores | Single-Core Score | Multi-Core Score | % Increase |
| 1 | 1 | 3159 | 2976 | base |
| 1 | 2 | 3161 | 4758 | ↑60% |
| 1 | 4 | 3055 | 5068 | ↑70% |
| 2 | 1 | 2991 | 4820 | ↑62% |
| 4 | 1 | 2960 | 4931 | ↑65% |
| 2 | 2 | 2913 | 5060 | ↑70% |
The results here were pretty astonishing, as soon as we increase the CPU count we actually lost single-core performance and gained a slightly higher multi-core score.
This may be because of the way VMware handle cores vs CPU’s. It could also be because of how the guest operating system handles multiple processors. Regardless, seeing as single-thread performance is more important in most applications, I’d stick with adding cores and not processors for the time being.
Recent Comments