utility is used for controlling realtime process scheduling.
utility is used for controlling idletime process scheduling, and can be called
with the same options as
A process with a realtime priority is not subject to priority
degradation, and will only be preempted by another process of equal or
higher realtime priority.
A process with an idle priority will run only when no other
process is runnable and then only if its idle priority is equal or
greater than all other runnable idle priority processes.
when called without arguments will return the realtime priority
of the current process.
is called with 1 argument, it will return the realtime priority
of the process with the specified
is specified, the process or program is run at that realtime priority.
is specified, the process or program is run as a normal (non-realtime)
is specified, the process with the process identifier
will be modified, else if
is specified, that program is run with its arguments.
is an integer between 0 and RTP_PRIO_MAX (usually 31).
0 is the
of 0 means "the current process".
Only root is allowed to set realtime or idle priority for a process.
A user may modify the idle priority of their own processes if the
is set to non-zero.
Note that this increases the chance that a deadlock can occur
if a process locks a required resource and then does
not get to run.
To see which realtime priority the current process is at:
To see which realtime priority of process 1423:
at the lowest realtime priority:
rtprio 31 cron
To change the realtime priority of process 1423 to 16:
rtprio 16 -1423
without realtime priority:
rtprio -t tcpdump
To change the realtime priority of process 1423
rtprio -t -1423
To make depend while not disturbing other machine usage:
idprio 31 make depend
There is no way to set/view the realtime priority of process 0
There is in
no way to ensure that a process page is present in memory therefore
the process may be stopped for pagein (see
system calls are currently never preempted, therefore non-realtime
processes can starve realtime processes, or idletime processes can
starve normal priority processes.