Component-based Analysis of Worst-case Temperatures

Transcription

1 Component-based Analysis of Worst-case Temperatures Lothar Thiele, Iuliana Bacivarov, Jian-Jia Chen, Devendra Rai, Hoeseok Yang 1

2 How can we analyze timing properties in a compositional framework? 2

3 Modular System Composition CPU BUS DSP RM TDMA TDMA GPC GPC GSC GPC GPC GPC Swiss Federal Institute of Technology 3 Computer Engineering and Networks Laboratory

4 When does it get hot? 4

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6 Can we determine worst case temperatures in such a compositional framework? 6

7 Contents " Single Component Simple Example Models Results Simulations " Composition " Concluding Remarks 7

8 bound on event arrivals period: 120 ms jitter: 240 ms interarrival: 30 ms workload model execution time: 30ms 8

9 bound on event arrivals period: 120 ms jitter: 240 ms interarrival: 30 ms workload model execution time: 30ms peak temperatures average workload of tasks (25%): 342.5K random trace (500 s): K reasonable heuristic: K worst case: K 9

10 heuristic worst case 10

11 Given a bound on workload arrivals (arrival curves) a computation model (from workload to task executions) a power model (from task executions to power) a temperature model (from power to temperature) What is the worst case peak temperature? 11

12 Contents " Single Component Simple Example Models Results Simulations " Composition " Concluding Remarks 12

13 " Workload Arrival Model Cumulative workload: In time interval [s, t), tasks with an accumulated workload of R(s,t) arrive. Arrival curve: The cumulative workload is upper bounded by the arrival curve: Multiple inputs: 13

14 Event Stream workload R(2.5): total workload in t=[ ] ms 2.5 t [ms] t Arrival Curve α events α Δ maximum workload in any interval of length 2.5 ms 2.5 Δ [ms] 14

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18 " Computation Model Arriving workload is buffered in FIFO Work conserving schedule (EDF, FP, GPS, ) FIFO buffer cumulative workload accumulated computing time 18

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20 " Computation Model Bound on the computing time FIFO buffer arrival curve (tight!) computing time bound 20

21 Given bound on task arrivals : all feasible accumulated computing times are bounded by active mode idle mode 21

22 " Power Model active and idle modes temperature-dependent leakage " Temperature Model environment temperature I P thermal capacity thermal conductance G V T C V 0 T 0 22

23 What is the worst-case task arrival sequence that leads to maximal peak temperature? 23

24 Contents " Single Component Simple Example Models Results Simulations " Composition " Concluding Remarks 24

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26 reverse time maximal temperature 26

27 Does there exist a feasible input trace that leads to the peak temperature? FIFO buffer w.c. cumulative workload w. c. accumulated computing time 27

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29 maximal temperature 29

30 How large should be? 30

31 Contents " Single Component Simple Example Models Results Simulations " Composition " Concluding Remarks 31

32 bound on event arrivals period: 120 ms jitter: 240 ms interarrival: 30 ms workload model execution time: 30ms peak temperatures average workload of tasks (25%): 342.5K random trace (500 s): K reasonable heuristic: K worst case: K 32

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35 worst case peak temperature 100 random simulations 35

36 not schedulable under EDF schedulable under EDF change task arrival of video 36

37 Contents " Single Component Simple Example Models Simulations " Composition " Concluding Remarks 37

38 Application Scenario " MPEG-2 decoding: Picture-in-picture application high resolution Output Device input rate low resolution constant read rate 38

39 Complete System Composition t Δ 39

40 Scenario " Model Calibration: SimpleScalar Simulation 1.3 GHz 3 GHz 8Mbps 576 macrobl macrobl GHz 1 frame 2 frames frames/s

41 Input Characterization

42 Application Scenario Time/Space questions: We know how to do that Do buffers overflow? Output Device Do buffers overflow or underflow? 42

43 Application Scenario Temperature question Maximal Temperature? Output Device 43

44 Analysis Results 44

45 Worst Case Temperature 45

46 Contents " Single Component Simple Example Models Simulations " Composition " Concluding Remarks 46

47 Critical instance for real-time analysis time 47

48 Critical instance for temperature analysis time maximal temperature 48

49 " Multiprocessor Extensions complex heat propagation explicit solution complex model reduction necessary Intel SCC " General Problems how to determine power model? how to determine temperature model? 49