performance limitation

A recent discussion on the Linux Kernel mailing list noted that threaded 64-bit applications suffer a drastic slowdown in pthread_create performance when stack utilization goes above 4GB.

Ingo Molnar offered an explanation of the problem, "unfortunately MAP_32BIT use in 64-bit apps for stacks was apparently created without foresight about what would happen in the MM when thread stacks exhaust 4GB.