Structural hazard - number of instructions

One of the indicators used to evaluate  the efficiency of the program execution is CPI (Clock cycles Per Instruction). It gives the information about average clock cycles required to execute one instruction. For the sequential processor that has a 5-stage execution unit and each stage requires one clock cycle, CPI value is 5. The lower the CPI value is better.

CPI value can be easily calculated taking the number of instructions that program contains and the number of clock cycles required to execute that program.