So, that does 19999 fork()s in 224 seconds, which works out to about 11 milliseconds per fork(). (On my Linux box, it's actually doing clone(), and also does a bunch of wait4(), rt_sigaction(), exit_group(), etc., but let's assume the fork() is the bottleneck.)
This is pretty slow, but it's still about 6× faster than the 70 milliseconds I had inferred from your "100× slower than any other POSIX".
Also note that your Red Hat machine is evidently forking in 39μs, which is several times faster than I've ever seen Linux fork.
So, that does 19999 fork()s in 224 seconds, which works out to about 11 milliseconds per fork(). (On my Linux box, it's actually doing clone(), and also does a bunch of wait4(), rt_sigaction(), exit_group(), etc., but let's assume the fork() is the bottleneck.)
This is pretty slow, but it's still about 6× faster than the 70 milliseconds I had inferred from your "100× slower than any other POSIX".
Also note that your Red Hat machine is evidently forking in 39μs, which is several times faster than I've ever seen Linux fork.