pcntl_setpriority — Change the priority of any process
pcntl_setpriority() sets the priority of pid .
priority is generally a value in the range -20 to 20. The default priority is 0 while a lower numerical value causes more favorable scheduling. Because priority levels can differ between system types and kernel versions, please see your system's setpriority(2) man page for specific details.
If not specified, the pid of the current process is used.
One of PRIO_PGRP, PRIO_USER or PRIO_PROCESS.
Returns TRUE on success or FALSE on failure.