Fig 1

1. Fig 1 Multimedia tasks (processes or threads) performance requirements (via system calls) monitoring scheduling SRT Scheduler demand distribution Profiler time allocation GRACE-OS Speed Adaptor speed scaling CPU

2. Fig 2 jth job (j+1)th job out in finish/out in finish/out in out in out in c1 c2 c3 c4 c5 c7 c8 c9 c10 c6 cycles cycles for jth job = (c2 – c1) + (c4 – c3) cycles for (j+1)th job = (c6 – c5) + (c8 – c7) + (c10 – c9) legend in profiled task is switched in for execution out profiled task is switched out for suspension finish profiled task finishes a job

3. b1 b2 Fig 3 1 cumulative distribution function F(x) cumulative probability Cmin=b0 br=Cmax br-1 cycle demand

4. b1 b2 Fig 4 statistical performance requirement 1 p cumulative probability Cmin=b0 br=Cmax bm cycle demand cycle allocation C

5. Fig 5 cycle: speed: 0 100 MHz 1 x 106 120 MHz 2 x 106 180 MHz 3 x 106 300 MHz (a) Speed schedule with four scaling points 120 speed (MHz) 100 job1's cycles=1.6x10 6 time (ms) 10 15 180 120 speed (MHz) 100 job2's cycles = 2.5 x 10 6 time (ms) 10 18.3 21.1 300 speed (MHz) 180 120 100 job3's cycles = 3.9 x 10 6 time (ms) 10 18.3 23.8 26.8 (b) Speed scaling for three jobs using speed schedule in (a)

6. SRT tasks (processes or threads) • Instrumented with SRT APIs user level kernel level system calls process control block standard Linux scheduler • SRT-DVS modules • Soft real-time scheduling • PowerNow speed scaling hook Fig 6

7. process control block • SRT flag • cycle counter • cycle budget • speed schedule • current point • other attributes … scaling point (cycle, speed) (cycle, speed) speed increase … (cycle, speed) Fig 7

8. fig 8

9. fig 9

10. Table 4 (DVS overhead)

11. Fig 10-a

12. Fig 10-b

13. Fig 11-a

14. Fig 11-b

15. Fig 11-c

16. Fig 11-d

17. Table 6

18. Table 9-10

19. Fig 12

20. Fig 13

21. Fig 14

22. Eq 6-7 Eq 8-10

23. Eq 11-12 Eq 13