RTS/GC resize_nursery: Calculation incorrectly assumes space taken up by the nursery is not usable by the nursery.
We set the size of the nursery based on:
* Formula: suggested - needed
* ----------------------------
* 1 + g0_pcnt_kept/100
*
* 'needed' is the amount of memory needed at the next
* collection for collecting all gens except g0.
However looking at the calculation of needed in calcNeeded
I don't see anything that would exclude the size of the nursery for needed
.
It's not super high impact but means nursery sizes are slightly smaller than they should be affecting performance negatively.