Libor> Do you know which architecture was the impetus for a 4th
Libor> page table level?
x86-64 I believe. x86-64 actually always uses 4 levels in HW but
Linux had to make one of them trivial, which limited a single memory
map to 512 GB. Apparently some workloads that mmap'ed a lot of giant
files actually ran into this limit.
- R.