rtsched(1) General Commands Manual rtsched(1)
NAME
rtsched - execute process/lightweight process (LWP) with real-time priority
SYNOPSIS
scheduler priority command [arguments]
scheduler] priority
scheduler] priority
scheduler] priority
DESCRIPTION
executes command with POSIX or HP-UX real-time priority, or changes the real-time priority of currently executing process (pid) or light-
weight process (lwpid).
All POSIX real-time priority processes or LWPs are of greater scheduling importance than processes/LWPs with HP-UX real-time or HP-UX time-
share priority. All HP-UX real-time priority processes/LWPs are of greater scheduling importance than HP-UX timeshare priority pro-
cesses/LWPs, but are of lesser importance than POSIX real-time processes/LWPs.
Neither POSIX nor HP-UX real-time processes/LWPs are subject to degradation.
POSIX real-time processes/LWPs may be scheduled with one of three different POSIX real-time schedulers: SCHED_FIFO, SCHED_RR, or SCHED_RR2.
See rtsched(2) for details.
is a superset of See rtprio(1).
Options
Specify the desired scheduler:
POSIX real-time schedulers: SCHED_FIFO
SCHED_RR
SCHED_RR2
HP-UX real-time scheduler: SCHED_RTPRIO
HP-UX timeshare scheduler: SCHED_HPUX
SCHED_NOAGE
Specify priority range;
any integer within the inclusive priority range of the corresponding scheduler. is required for all schedulers except
SCHED_HPUX. If scheduler is SCHED_HPUX, the priority argument is ignored. The default priority range of each scheduler is
as follows:
scheduler highest priority lowest priority
--------------------------------------------------
SCHED_FIFO 31 0
SCHED_RR 31 0
SCHED_RR2 31 0
SCHED_RTPRIO 0 127
SCHED_NOAGE 178 255
SCHED_HPUX N/A N/A
Higher numerical values for the priority represent higher priorities under POSIX real-time schedulers, whereas lower numeri-
cal values for the priority represent higher priorities under HP-UX real-time and timeshare schedulers.
Specify an already executing
process ID (pid).
Specify an already executing
lightweight process ID (lwpid). The target LWP (lwpid) can be in any process.
Select all the LWPs in an already executing
process (specified with When scheduling policy is not specified explicitly using the option, the process's current schedul-
ing policy will be used. If the requested priority value is in the range for this scheduling policy, the scheduling policy
and priority of the process and all its LWPs will be changed to these values. Please note that it may cause the scheduling
policy to be changed for some LWPs.
If the user is not a member of a group having access and is not the user with appropriate privileges, command is not scheduled, or pid's/
lwpid's real-time priority is not changed. When changing the real-time priority of a currently executing process/LWP, the effective 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.
In presence of processor sets (see pset_create(2) for details), the application execution is restricted to processors in the application's
processor set. The threads in different processor sets do not compete with one another for processors based on their scheduling policy and
priority values. The scheduler looks only at threads assigned to a processor's processor set to choose the next thread to run.
RETURN VALUE
returns exit status:
if command is successfully scheduled or if pid's or lwpid's real-time priority is successfully changed;
if command is not executable, pid or lwpid does not exist, or priority is not within the priority range for the corresponding
scheduler;
if command (pid/lwpid) lacks real-time capability, or the invoker's effective user ID is not a user who has appropriate privi-
leges, 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; or
if rtsched encountered an internal
error or if rtsched is not supported by this release.
EXAMPLES
Execute file with SCHED_FIFO at a priority of 10:
Execute file with SCHED_RTPRIO at a priority of 127 (this is synonymous to
Execute file with the SCHED_HPUX scheduler:
This is useful to spawn a timeshare priority command from a real-time priority shell.
Set the currently running process, pid 24217, to execute with SCHED_RR2 at a priority of 20:
Now change its priority to 10 using the same scheduler:
Set the currently running LWP, lwpid 987312, to execute with SCHED_RR at a priority of 10:
Set all currently executing LWPs in a process pid 21342 to execute with SCHED_FIFO at a priority of 25:
WARNINGS
The priority values used by may differ from those used by other commands. For example, ps(1) displays the internal representation of pri-
ority values.
AUTHOR
was developed by HP.
SEE ALSO
rtprio(1), setprivgrp(1M), getprivgrp(2), pset_create(2), rtprio(2), rtsched(2), _lwp_getscheduler(2), _lwp_setscheduler(2),
pstat_getlwp(2).
rtsched(1)