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rtprio(1) [freebsd man page]

RTPRIO(1)						    BSD General Commands Manual 						 RTPRIO(1)

NAME
rtprio, idprio -- execute, examine or modify a utility's or process's realtime or idletime scheduling priority SYNOPSIS
[id|rt]prio [id|rt]prio [-]pid [id|rt]prio priority command [args] [id|rt]prio priority -pid [id|rt]prio -t command [args] [id|rt]prio -t -pid DESCRIPTION
The rtprio utility is used for controlling realtime process scheduling. The idprio utility is used for controlling idletime process scheduling, and can be called with the same options as rtprio. 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. Both rtprio or idprio when called without arguments will return the realtime priority of the current process. If rtprio is called with 1 argument, it will return the realtime priority of the process with the specified pid. If priority is specified, the process or program is run at that realtime priority. If -t is specified, the process or program is run as a normal (non-realtime) process. If -pid is specified, the process with the process identifier pid will be modified, else if command is specified, that program is run with its arguments. Priority is an integer between 0 and RTP_PRIO_MAX (usually 31). 0 is the highest priority Pid 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 sysctl(8) variable security.bsd.unprivileged_idprio 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. EXIT STATUS
If rtprio execute a command, the exit value is that of the command executed. In all other cases, rtprio exits 0 on success, and 1 for all other errors. EXAMPLES
To see which realtime priority the current process is at: rtprio To see which realtime priority of process 1423: rtprio 1423 To run cron(8) at the lowest realtime priority: rtprio 31 cron To change the realtime priority of process 1423 to 16: rtprio 16 -1423 To run tcpdump(1) without realtime priority: rtprio -t tcpdump To change the realtime priority of process 1423 to RTP_PRIO_NORMAL (non-realtime/normal priority): rtprio -t -1423 To make depend while not disturbing other machine usage: idprio 31 make depend SEE ALSO
nice(1), ps(1), rtprio(2), setpriority(2), nice(3), renice(8) HISTORY
The rtprio utility appeared in FreeBSD 2.0, but is similar to the HP-UX version. AUTHORS
Henrik Vestergaard Draboel <hvd@terry.ping.dk> is the original author. This implementation in FreeBSD was substantially rewritten by David Greenman. CAVEATS
You can lock yourself out of the system by placing a cpu-heavy process in a realtime priority. BUGS
There is no way to set/view the realtime priority of process 0 (swapper) (see ps(1)). There is in FreeBSD no way to ensure that a process page is present in memory therefore the process may be stopped for pagein (see mprotect(2), madvise(2)). Under FreeBSD system calls are currently never preempted, therefore non-realtime processes can starve realtime processes, or idletime pro- cesses can starve normal priority processes. BSD
September 29, 2012 BSD

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RENICE(8)						    BSD System Manager's Manual 						 RENICE(8)

NAME
renice -- alter priority of running processes SYNOPSIS
renice priority [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...] renice -n increment [[-p] pid ...] [[-g] pgrp ...] [[-u] user ...] DESCRIPTION
The renice utility alters the scheduling priority of one or more running processes. The following who parameters are interpreted as process ID's, process group ID's, user ID's or user names. The renice'ing of a process group causes all processes in the process group to have their scheduling priority altered. The renice'ing of a user causes all processes owned by the user to have their scheduling priority altered. By default, the processes to be affected are specified by their process ID's. The following options are available: -g Force who parameters to be interpreted as process group ID's. -n Instead of changing the specified processes to the given priority, interpret the following argument as an increment to be applied to the current priority of each process. -u Force the who parameters to be interpreted as user names or user ID's. -p Reset the who interpretation to be (the default) process ID's. Users other than the super-user may only alter the priority of processes they own, and can only monotonically increase their ``nice value'' within the range 0 to PRIO_MAX (20). (This prevents overriding administrative fiats.) The super-user may alter the priority of any process and set the priority to any value in the range PRIO_MIN (-20) to PRIO_MAX. Useful priorities are: 20 (the affected processes will run only when nothing else in the system wants to), 0 (the ``base'' scheduling priority), anything negative (to make things go very fast). FILES
/etc/passwd to map user names to user ID's EXAMPLES
Change the priority of process ID's 987 and 32, and all processes owned by users daemon and root. renice +1 987 -u daemon root -p 32 SEE ALSO
nice(1), rtprio(1), getpriority(2), setpriority(2) STANDARDS
The renice utility conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
The renice utility appeared in 4.0BSD. BUGS
Non super-users cannot increase scheduling priorities of their own processes, even if they were the ones that decreased the priorities in the first place. BSD
June 9, 1993 BSD
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