Reevaluating Amdahl's Law in the Multicore Era

Event Sponsor: 
LANS Informal Seminar
Start Date: 
Feb 17 2010 - 3:00pm to 4:00pm
Building 240, Rm 1404-1405
Argonne National Laboratory
Xian-He Sun,
Speaker(s) Title: 
Professor and Chairman of the Dept. of Computer Science at Illinois Institute of Technology.

Multicore architecture has become the trend of high performance processors. While it is generally accepted that we have entered the multicore era, concerns exist on when or will moving into the manycore stage. Recently, Hill and Marty presented a pessimistic view of multicore scalability, citing Amdahl's law and the memory-wall problem. Technology is available, but major vendors are hesitant in making processors that have a large number of cores. This is a very interesting phenomenon, where history seems to repeat itself on the scalability debate of parallel processing that occurred 20 years ago. In this introductory talk we first review the history and concepts of scalable computing, and review the current technologies and the memory-wall problem. We then use the same hardware cost model of multicore chips used by Hill and Marty to introduce two performance models from the scalable computing point of view. These models show that there is no inherent, immovable upper bound on the scalability of multicore architectures. Finally, we conclude with proposed solutions to the memory-wall problem to make the potential scalability of multicore reachable in practice.

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