Blog Series Looks At Amdahl’s Law for Comparing Parallel Systems

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The speedup of a program using multiple processors in parallel computing is limited by the sequential fraction of the program.

Over at Moor Insights & Strategy Paul Teich has posted an in-depth series of features looking at Amdahl’s Law, documenting a “middle-out” model for measuring the impact of parallel computing choices.


Gene Amdahl’s eponymous equation is a general, theoretical, top-down definition of the relative performance speedup that might be obtained by increasing the parallelism of a specific system. It is somewhat useful for describing the high-level effects of adding or subtracting more parallel processing resources to an existing system or tuning the balance of “serial” vs. parallel code. But it does not provide insight into the performance trade-offs of today’s heterogeneous architectures and says nothing at all about power consumption. In other words, Amdahl’s Law is more what you’d call a guideline than an actual law.

Teich says he wrote these posts to help companies make competitive comparisons between systems, without getting mired in subtle details and complex low-level interactions. Read the Full Story.