chrt(1) - phpMan

CHRT(1) User Commands CHRT(1)

NAME
chrt - manipulate the real-time attributes of a process

SYNOPSIS
chrt [options] prio command [arg]...
chrt [options] -p [prio] pid

DESCRIPTION
chrt sets or retrieves the real-time scheduling attributes of an existing pid, or runs
command with the given attributes. Both policy (one of SCHED_OTHER, SCHED_FIFO, SCHED_RR,
SCHED_BATCH, or SCHED_IDLE) and priority can be set and retrieved.

The SCHED_BATCH policy is supported since Linux 2.6.16. The SCHED_IDLE policy is sup-
ported since Linux 2.6.23.

The SCHED_RESET_ON_FORK flag for policies SCHED_RR and SCHED_FIFO is supported since Linux
2.6.31.

OPTIONS
-a, --all-tasks
Set or retrieve the scheduling attributes of all the tasks (threads) for a given
PID.

-b, --batch
Set scheduling policy to SCHED_BATCH (Linux specific).

-f, --fifo
Set scheduling policy to SCHED_FIFO.

-i, --idle
Set scheduling policy to SCHED_IDLE (Linux specific).

-m, --max
Show minimum and maximum valid priorities, then exit.

-o, --other
Set policy scheduling policy to SCHED_OTHER.

-p, --pid
Operate on an existing PID and do not launch a new task.

-r, --rr
Set scheduling policy to SCHED_RR. When policy is not defined the SCHED_RR is used
as default.

-R, --reset-on-fork
Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR scheduling policy (Linux
specific).

-v, --verbose
Show status information.

-h, --help
Display usage information and exit.

-V, --version
Display version information and exit.

USAGE
The default behavior is to run a new command:
chrt prio command [arguments]

You can also retrieve the real-time attributes of an existing task:
chrt -p pid

Or set them:
chrt -r -p prio pid

PERMISSIONS
A user must possess CAP_SYS_NICE to change the scheduling attributes of a process. Any
user can retrieve the scheduling information.

NOTES
Only SCHED_FIFO, SCHED_OTHER and SCHED_RR are part of POSIX 1003.1b Process Scheduling.
The other scheduling attributes may be ignored on some systems.

Linux default scheduling policy is SCHED_OTHER.

AUTHOR
Written by Robert M. Love.

COPYRIGHT
Copyright (C) 2004 Robert M. Love
This is free software; see the source for copying conditions. There is NO warranty; not
even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.