spice

ng number of threads you learn something more interesting: The scheduler in Rayon is actually pretty good at giving work to separate threads, but the overall work execution mechanism has a ~15 ns overhead. Despite this being an utterly useless program we've learnt something that we can apply later on: Our smallest unit of work should probably be a bit bigger than ~7 ns before we reach for Rayon. (Unless it's more important for use to reduce overall latency at the cost of the throughput of the whole system.) In comparison, if you read the Rayon documentation they will not attempt to give you any number. They just say "Conceptually, calling join() is similar to spawning two threads, one executing each of the two closures. However, the implementation is quite different and incurs very low overhead": https://docs.rs/rayon/latest/rayon/fn.join.html. (Also: If I wanted to be misleading I would say "Spice is twice as fast as Rayon since it gets 10x speed-up compared to 4.5x speed-up")