1. MS108 Computer System I Lecture 2 Metrics Prof. Xiaoyao Liang 2014/2/28 1

2. Performance Metrics 2

3. 3

4. CPI 4

5. IPC 5

6. IPC 6

7. Amdahl’s Law 7

8. 8

9. 9

10. Performance Equation 10 The Processor Performance Equation

11. 11 Performance Equation

12. 12 Different instruction types having different CPIs

13. 13MIPS

14. 14MFLOPS

15. 15GHz

16. 16

17. 17

18. 18 IC Cost Cost driven down by learning curve –Yield DRAM: price closely tracks cost Microprocessors: price depends on volume –10% less for each doubling of volume

19. IC Cost 19 Integrated circuit Bose-Einstein formula: Defects per unit area = 0.016-0.057 defects per square cm (2010) N = process-complexity factor = 11.5-15.5 (40 nm, 2010)

20. IC Cost 20

21. Availability Year 21

22. Power 22

23. Power 23

24. Power 24 Dynamic energy –Transistor switch from 0 -> 1 or 1 -> 0 –½1/2 x Capacitive load x Voltage 2 Dynamic power –½ 1/2x Capacitive load x Voltage 2 x Frequency switched Reducing clock rate reduces power, not energy

25. Power 25 Static power consumption –Current static x Voltage –Scales with number of transistors –To reduce: power gating

26. Power 26 Intel 80386 consumed ~ 2 W 3.3 GHz Intel Core i7 consumes 130 W Heat must be dissipated from 1.5 x 1.5 cm chip This is the limit of what can be cooled by air

27. Benchmark 27

28. Benchmark 28

29. 29Benchmark