| .\" chrt(1) manpage |
| .\" |
| .\" Copyright (C) 2004 Robert Love |
| .\" |
| .\" This is free documentation; you can redistribute it and/or |
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| .\" GNU General Public License for more details. |
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| .\" 2002-05-11 Robert Love <rml@tech9.net> |
| .\" Initial version |
| .\" |
| .TH CHRT "1" "Apr 2003" "schedutils" "Linux User's Manual" |
| .SH NAME |
| chrt \- manipulate real-time attributes of a process |
| .SH SYNOPSIS |
| .B chrt |
| .RI [ options ]\ prio |
| .IR command\ [ arg ]... |
| .br |
| .B chrt |
| .RI [ options ] |
| .B \-p |
| .RI [ prio ]\ pid |
| .SH DESCRIPTION |
| .PP |
| .BR 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 |
| .BR SCHED_OTHER , |
| .BR SCHED_FIFO , |
| .BR SCHED_RR , |
| .BR SCHED_BATCH , |
| or |
| .BR SCHED_IDLE ) |
| and priority can be set and retrieved. |
| .PP |
| The |
| .BR SCHED_BATCH |
| policy is supported since Linux 2.6.16. The |
| .BR SCHED_IDLE |
| policy is supported since Linux 2.6.23. |
| .SH OPTIONS |
| .TP |
| .B -p, --pid |
| operate on an existing PID and do not launch a new task |
| .TP |
| .B -b, --batch |
| set scheduling policy to |
| .BR SCHED_BATCH |
| (Linux specific) |
| .TP |
| .B -f, --fifo |
| set scheduling policy to |
| .BR SCHED_FIFO |
| .TP |
| .B -i, --idle |
| set schedulng policy to |
| .BR SCHED_IDLE |
| (Linux specific) |
| .TP |
| .B -m, --max |
| show minimum and maximum valid priorities, then exit |
| .TP |
| .B -o, --other |
| set policy scheduling policy to |
| .BR SCHED_OTHER |
| .TP |
| .B -r, --rr |
| set scheduling policy to |
| .BR SCHED_RR |
| (the default) |
| .TP |
| .B -h, --help |
| display usage information and exit |
| .TP |
| .B -v, --version |
| output version information and exit |
| .SH USAGE |
| .TP |
| The default behavior is to run a new command:: |
| chrt prio command [arguments] |
| .TP |
| You can also retrieve the real-time attributes of an existing task: |
| chrt -p pid |
| .TP |
| Or set them: |
| chrt -p prio pid |
| .SH PERMISSIONS |
| A user must possess |
| .BR CAP_SYS_NICE |
| to change the scheduling attributes of a process. Any user can retrieve the |
| scheduling information. |
| .SH NOTES |
| Only |
| .BR SCHED_FIFO , |
| .BR SCHED_OTHER |
| and |
| .BR SCHED_RR |
| are part of POSIX 1003.1b Process Scheduling. The other scheduling attributes |
| may be ignored on some systems. |
| .SH AUTHOR |
| Written by Robert M. Love. |
| .SH COPYRIGHT |
| Copyright \(co 2004 Robert M. Love |
| .br |
| This is free software; see the source for copying conditions. There is NO |
| warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| .SH "SEE ALSO" |
| .BR taskset (1), |
| .BR nice (1), |
| .BR renice (1) |
| .sp |
| See |
| .BR sched_setscheduler (2) |
| for a description of the Linux scheduling scheme. |
| .SH 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/. |
