[ashdnazg]

Interesting article!

Regarding the low core-count, you might actually lose performance when having less CGUs, since your absolute estimation error is larger.

For example if a CGU can take 3 times as long to compile as another with the same estimate, we might end up with a 0.75:0.25 split if we have 2 CGUs, ending up with a 50% increase in compilation time, but with 16 CGUs the worst case (one CGU taking a 1/6 of the time and 15 CGUs taking 1/18 of the time) will only result in ~11% increase in compilation time, due to the automatic balancing that job scheduling gives us.

[kevincox]

I had the same thought. It may be interesting to try producing smaller CGUs then processing them on a fixed-size thread pool. This should help even out the misses. Especially if you keep a few smaller CGUs for the end, they should be "free" to give to threads that would otherwise be finished compared to merging them into a different CGU which may happen to be under-estimated and take longer.