单周期、多周期、流水线控制性能比较 Single-Cycle EXecution Tok=350+250+350+350+250=1550ps IF RegI alU mEm Reg CPI=1, but long clock cycle Each instruction 1550 ps IFRegI ALU MEM Reg Each instruction=1550 ps IF RegI ALU MEM Reg lulti-Cycle Execution: Toock=350 ps Each instruction= 1550 ps-+ F Regalo|MEM| Reg Average CPI=5×02+4×0.1+4×04+3×0.3=39 350ps" 350ps 350ps IF Regl ALu Reg Load =5 cycles 350ps 350ps 350ps 350ps Reg ALU ALU =4 cycles 350ps350ps350ps Pipelined execution Branch=3 cycles→ IFReg ALU MEMReg cock=350ps=max(350,250) 350ps Reg ALU MEM Reg One instruction completes each cycle 350psIFReg ALU Reg Average CPI=1 350ps 350ps 350ps350ps 350ps ignore time to fill pipeline 中国科学技术大学 chapter 12单周期、多周期、流水线控制性能比较 • 假设5段指令执行流水线 • 某一程序段假设： – 20% load, 10% store, 40% ALU, and 30% branch • 比较三种执行模式的性能 中国科学技术大学 chapter03.12