chrt(1)
NAME
chrt - manipulate the real-time attributes of a process
SYNOPSIS
chrt [options] priority command [argument...] chrt [options] -p [priority] pid
DESCRIPTION
chrt sets or retrieves the real-time scheduling attributes of an existing pid, or runs command with the given attributes.
POLICIES
-o, --other
Set scheduling policy to SCHED_OTHER. This is the default Linux
scheduling policy.
-f, --fifo
Set scheduling policy to SCHED_FIFO.
-r, --rr
Set scheduling policy to SCHED_RR. When no policy is defined,
the SCHED_RR is used as the default.
-b, --batch
Set scheduling policy to SCHED_BATCH (Linux-specific, supported
since 2.6.16). The priority argument has to be set to zero.
-i, --idle
Set scheduling policy to SCHED_IDLE (Linux-specific, supported
since 2.6.23). The priority argument has to be set to zero.
-d, --deadline
Set scheduling policy to SCHED_DEADLINE (Linux-specific,
supported since 3.14). The priority argument has to be set to
zero. See also --sched-runtime, --sched-deadline and
--sched-period. The relation between the options required by
the kernel is runtime <= deadline <= period. chrt copies period
to deadline if --sched-deadline is not specified and deadline to
runtime if --sched-runtime is not specified. It means that at
least --sched-period has to be specified. See sched(7) for more
details.
SCHEDULING OPTIONS
-T, --sched-runtime nanoseconds
Specifies runtime parameter for SCHED_DEADLINE policy (Linux-
specific).
-P, --sched-period nanoseconds
Specifies period parameter for SCHED_DEADLINE policy (Linux-
specific).
-D, --sched-deadline nanoseconds
Specifies deadline parameter for SCHED_DEADLINE policy (Linux-
specific).
-R, --reset-on-fork
Add SCHED_RESET_ON_FORK flag to the SCHED_FIFO or SCHED_RR
scheduling policy (Linux-specific, supported since 2.6.31).
OPTIONS
-a, --all-tasks
Set or retrieve the scheduling attributes of all the tasks
(threads) for a given PID.
-m, --max
Show minimum and maximum valid priorities, then exit.
-p, --pid
Operate on an existing PID and do not launch a new task.
-v, --verbose
Show status information.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
USAGE
The default behavior is to run a new command:
chrt priority command [arguments]
You can also retrieve the real-time attributes of an existing task:
chrt -p pid
Or set them:
chrt -r -p priority 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.
SEE ALSO
taskset(1), nice(1), renice(1), sched(7) See sched_setscheduler(2) for a description of the Linux scheduling scheme.
AUTHORS
Robert Love rml@tech9.net Karel Zak kzak@redhat.com
AVAILABILITY
The chrt command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
