rtprio(1) [hpux man page]
rtprio(1) General Commands Manual rtprio(1) NAME
rtprio - execute process with real-time priority SYNOPSIS
priority command [arguments] priority command [arguments] DESCRIPTION
executes command with a real-time priority, or changes the real-time priority of currently executing process pid. Real-time priorities range from zero (highest) to 127 (lowest). Real-time processes are not subject to priority degradation, and are all of greater (schedul- ing) importance than non-real-time processes. See rtprio(2) for more details. If is specified instead of a real-time priority, executes command with a timeshare (non-real-time) priority, or changes the currently exe- cuting process pid from a possibly real-time priority to a timeshare priority. The former is useful to spawn a timeshare priority command from a real-time priority shell. If is not specified, command is not scheduled, or pid's real-time priority is not changed, if the user is not a member of a group having access and is not the user with appropriate privileges. When changing the real-time priority of a currently executing process, the effec- tive user ID of the calling process must be the user with appropriate privileges, or the real or effective user ID must match the real or saved user ID of the process to be modified. RETURN VALUE
returns exit status 0 if command is successfully scheduled or if pid's real-time priority is successfully changed, 1 if command is not exe- cutable or pid does not exist, and 2 if command (pid) lacks real-time capability, or the invoker's effective user ID is not a user who has appropriate privileges, or the real or effective user or the real or effective user ID does not match the real or saved user ID of the process being changed. EXAMPLES
Execute file at a real-time priority of 100: Set the currently running process pid 24217 to a real-time priority of 40: AUTHOR
was developed by HP. SEE ALSO
setprivgrp(1M), getprivgrp(2), rtprio(2). rtprio(1)
Check Out this Related 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