GNU/Linux systems running servers that spawns a process for each connection should be configured at compile-time to handle many processes.
1.1 Tuning NR_TASKS
The default number of maximum tasks in the Linux kernel is set to 512.
This is defined by NR_TASKS in $BUILDDIR/linux/include/linux/tasks.h
It's recommended changing NR_TASKS from 512 to (at least) 2048 and changing MIN_TASKS_LEFT_FOR_ROOT to 24
-- ChristopherMitchell - 04 Jun 2002