Amdahl's Law in the Multicore Era

Abstract

We apply Amdahl's Law to multicore chips using symmetric cores, asymmetric cores, and dynamic techniques that allows cores to work together on sequential execution. To Amdahl's simple software model, we add a simple hardware model based on fixed chip resources.

A key result we find is that, even as we enter the multicore era, researchers should still seek methods of speeding sequential execution. Moreover, methods that appear locally inefficient (e.g., tripling sequential performance with a 9x resource cost) can still be globally efficient as they reduce the sequential phase when the rest of the chip's resources are idle.