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Can you please once again explain how the comm-to-comp ratio is calculated? From what I see, elements communicated divided by elements computed (on the right-hand side) give us an O(N/sqrt(P)) per core, which multiplied with number of processors, gives us O(N*sqrt(P)) rather than O(sqrt(P)). Where did the N go? Or what am I missing?


@aeu, see next slide, here we consider problem-constrained scaling, where N is regarded constant since we are solving the same problem. You can take a look at the description of problem constrained scaling from previous slides.


@TanXiaoFengSheng Ah, excellent. Thank you for the clarification.