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SIMD-MIMD Real-Time Comparisons (Our Chapter 7). References: Stankovic, Spuri, Ramamritham, Buttazzo, “Deadline Scheduling for Real-Time Systems”, Kluwer, 1998, ISBN 0-7923-8269-2.
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SIMD-MIMD Real-Time Comparisons(Our Chapter 7) • References: • Stankovic, Spuri, Ramamritham, Buttazzo, “Deadline Scheduling for Real-Time Systems”, Kluwer, 1998, ISBN 0-7923-8269-2. • Stankovic, Spuri, Natale, Buttazzo, “Implications of Classical Scheduling Results for Real-Time Systems”, IEEE Computer, Vol. 28, No 6, pp. 16-25, June 1995. • Meilander, Jin, Baker, “Tractable Real-Time Air Traffic Control Automation”, Fourteenth IASTED International Conference on Parallel and Distributed Computing and Systems (PDCS’02), pp. 483-488, November 2002. • Meilander, Baker, Jin, “Importance of SIMD Computation Reconsidered”, working copy handout. • Initially we will go through most of the slides used for the presentation of the paper, “Tractable Real-Time Air Traffic Control Automation”. • Presentation given by Will Meilander at PDCS Conference in November 2002. • The PDCS slides will follow this set of slides. • A polynomial time MP solution to the ATC is not believed possible. In particular, • MP solutions to virtually all real-time problems today include an online solution to one or more dynamic scheduling problems. • Dynamic scheduling is an NP-hard problem. • The MP cannot solve most real-time problems using a static scheduling algorithm (to avoid using dynamic scheduling). Chapter 2
As observed in the earlier set of slides, a low order polynomial time solution to the ATC problem is possible on the AP. • Open Question: Does there exist a “splitting problem” that has a polynomial time solution using an AP but all solutions using an MP involve solving an additional problem that is NP-hard. • Additional restrictions can be made, if needed. • Such a result would establish that MPs are not more powerful than SIMDs, as is currently believed by many professionals in the area. • This work raises other open questions as well, both practical and theoretical. • How much can one move away from the SIMD architectures and programming style towards MIMD before encountering the MIMD difficulty • That is, of having to solve “NP-hard problems” in order to solve original problem • In particular, how can the multiple instruction streams for MASC interact so as to avoid this MIMD difficulty? Chapter 2