In our current MongoDB document Production Notes, under the VMware section, the following CPU reservation recommendation has been given to the customer:

When using MongoDB with VMware, ensure that the CPU reservation does not exceed more than 2 virtual CPUs per physical core. 

I am not aware of the historical reason why this is given to the customer, but VMware CPU reservation does not work like this. When setting up CPU reservation for a VM, you can not reserve number of vCPUs, but the CPU cycles (MHz). It is then the hypervisor's job to guaranty the reserved CPU cycles are available to the VM even if the ESXi host is under CPU resource contention.

I suggest removing the above recommendation from our Production Notes.