Parallel Computer Architecture

258 CHAPTER 4 Workload-Driven Evaluation

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2 4 8 16 32 64

Number of processors

FIGURE 4.18 Communication-to-computation ratio versus processor count for the base prob-

lem size in the six parallel applications

for the low communication-to-computation ratios is that the applications we are

using have been very well optimized in their assignments for parallel execution.

Applications used in practice, including other versions of these applications, may

exhibit higher communication-to-computation ratios.

The next observation from the figure is that the growth rates of communication-

to-computation ratios are very different across