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
• Minimizing 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