A simple, standalone parfib-like benchmark.
This benchmark performs a binary tree of strictly nested spawn/join
pairs. Each benchmark is structured so as to take a parameter, N,
and perform exactly N spawn join pairs.
Making the benchmark linear in its input parameter allows us to employ linear regression to accurately compute the exact per-spawn overhead in each implementation. It also lets us compare implementations with vastly different performance (e.g. threads versus tasks) which is difficult using a traditional parfib scheduler microbenchmark.
We use the criterion benchmarking tool to drive the benchmarks and perform the linear regression.