On Thu, 16 Dec 2021 21:37:26 GMT, kabutz <d...@openjdk.java.net> wrote:
> > embarrassingly parallelizable > > Having looked at [embarrassingly > parallel](https://en.wikipedia.org/wiki/Embarrassingly_parallel), I'm not > certain that this particular problem would qualify. The algorithm is easy to > parallelize, but in the end we still have some rather large numbers, so > memory will be our primary dominator. I'd expect to see a linear speedup if > it was "perfectly parallel", but this does not come close to that. I ran fibonacci(100_000_000) with multiply() and parallelMultiply(). For multiply() we had: real 0m25.627s user 0m26.767s sys 0m1.197s and for parallelMultiply() we had real 0m10.030s user 1m2.205s sys 0m2.489s Thus we are 2.5 times faster on a 1-6-2 machine, but use more than 2x the user time. If it were perfectly parallel, shouldn't we expect to see the parallelMultiply() be close to user time of 26s and real time 4.3s? ------------- PR: https://git.openjdk.java.net/jdk/pull/6409
