I have been umming and ahhing about this for a good while ,I can see the VMware Knowledge Base article here is useful.
Basically we need to look at this tid bit:
The behavior of two key storage counters affects the way the PVSCSI and LSI Logic adapters handle interrupt coalescing:
* Outstanding I/Os (OIOs): Represents the virtual machine’s demand for I/O.
* I/Os per second (IOPS): Represents the storage system’s supply of I/O.
I then found a good blog article in the wild which does a great job on explaining how to make that choise.
You can read about it at pivot point.