CHRT(1)                                                Linux User's Manual                                               CHRT(1)



NAME
       chrt - manipulate real-time attributes of a process

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

DESCRIPTION
       chrt(1)  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 supported 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
       -p, --pid
              operate on an existing PID and do not launch a new task

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

       -f, --fifo
              set scheduling policy to SCHED_FIFO

       -i, --idle
              set schedulng 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

       -r, --rr
              set scheduling policy to SCHED_RR (the 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 -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.

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 FIT-
       NESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       taskset(1), nice(1), renice(1)

       See sched_setscheduler(2) for a description of the Linux scheduling scheme.

AVAILABILITY
       The chrt command is part of the util-linux-ng package and is  available  from  ftp://ftp.kernel.org/pub/linux/utils/util-
       linux-ng/.



schedutils                                                  June 2010                                                    CHRT(1)