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Cost-Effective Parallel Computing David Wood and Mark Hill University of Wisconsin IEEE Computer 1995. Presented by Eric Wheeler. Theme. Obtaining sub-linear speedups when implementing a multiprocessor can still be worthwhile. Balanced Systems. Amdahl’s Dictum
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Cost-Effective Parallel ComputingDavid Wood and Mark HillUniversity of WisconsinIEEE Computer 1995 Presented by Eric Wheeler
Theme • Obtaining sub-linear speedups when implementing a multiprocessor can still be worthwhile.
Balanced Systems • Amdahl’s Dictum • For each MIPS of processing power need 1 MB memory. • Converse should be true, too.
Formalism • Speedup simply needs to exceed costup to be “cost-effective”
Remember Memory… • Previous views are processor centric. Memory can dominate cost!
Generalization • When memory dominates, costups can be much smaller than linear in the number of processors.
Takeaways • Balanced systems should be a goal. • Speedups do not have to be linear to be effective thanks to the peripheral costs of adding another whole machine.
Questions • What should you consider as “cost” when deciding if your project design was effective in light of this paper? • What other things can dominate the cost? • What happens to this theory if memory becomes essentially free (e.g. low power, high density, cheap nanoarrays)?