Proof CPU maximum frequency in VM

Solution 1:

It is totally possible for TurboBoost be enabled while, at the same time, hypervisor only reporting the base CPU frequency. However, it is unlikely that you will ever enjoy the 3.6 GHz boosted frequency: TurboBoost (especially on such old CPUs) is an opportunistic boost which only kick in when few cores (eg: 2) are loaded, an unlikely scenario for an hypervisor.

What @FreeJack suggested you in the comments above is to compare the CPU performance of your virtualized instance with a bare-metal, same-Xeon host boosted to 3.6 GHz. This would be a difficult task, as any other loads on the underlying hypervisor can alter the benchmark results.

That said, rather than trying to increase the frequency of such an old CPU (Ivy Xeons are ~8 years old now), I strongly suggest you to switch to a more modern hypervisor (Xeon Scalable or newer, possibly even something based on AMD Epyc 7002 or 7003): thanks to higher IPC and clock, you can instantly gain >50% more performance.