Parallel Efficiency (PE) reveals the inefficiency in splitting computation over processes and then communicating data between processes. As with GE, PE is a compound metric whose components reflects two important factors in achieving good parallel performance in code.
Ensuring even distribution of computational work across processes
Minimising time communicating data between processes
These are measured with Load Balance Efficiency and Communication Efficiency, and PE is defined as the product of these two sub-metrics:
PE = Load Balance * Communication Efficiency