I recall discussion (can't find now) that performance would be impacted for Linux if a syscall table lookup had to spill to a second page. That gives a limit of

I recall discussion (can't find now) that performance would be impacted for Linux if a syscall table lookup had to spill to a second page. That gives a limit of 512 64-bit pointers for syscalls we want to be high-performance, which may drive both OS's to start limiting new syscalls as they get close. I don't know if there's more to this claim than just concern about an extra TLB entry though.