taskset(1) manpage Copyright (C) 2004 Robert Love This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system, including intermediate and printed output. This manual is distributed in the hope that it will be use...
NAMEtaskset - set or retrieve a process's CPU affinity
SYNOPSIStaskset [options] mask command [argument...]
taskset [options] -p [mask] pid
taskset is used to set or retrieve the CPU affinity of a running process given its pid, or to launch a new command with a given CPU affinity. CPU affinity is a scheduler property that "bonds" a process to a given set of CPUs on the system. The Linux scheduler will honor the given CPU affinity and the process will not run on any other CPUs. Note that the Linux scheduler also supports natural CPU affinity: the scheduler attempts to keep processes on the same CPU as long as practical for performance reasons. Therefore, forcing a specific CPU affinity is useful only in certain applications.
The CPU affinity is represented as a bitmask, with the lowest order bit corresponding to the first logical CPU and the highest order bit corresponding to the last logical CPU. Not all CPUs may exist on a given system but a mask may specify more CPUs than are present. A retrieved mask will reflect only the bits that correspond to CPUs physically on the system. If an invalid mask is given (i.e., one that corresponds to no valid CPUs on the current system) an error is returned. The masks are typically given in hexadecimal. For example,
- is processor #0,
- is processors #0 and #1,
- is all processors (#0 through #31).
When taskset returns, it is guaranteed that the given program has been scheduled to a legal CPU.
- -a, --all-tasks
- Set or retrieve the CPU affinity of all the tasks (threads) for a given PID.
- -c, --cpu-list numbers
- Specify a numerical list of processors instead of a bitmask. The numbers are separated by commas and may include ranges. For example: 0,5,8-11.
- -p, --pid
- Operate on an existing PID and do not launch a new task.
- -V, --version
- Display version information and exit.
- -h, --help
- Display help text and exit.
- The default behavior is to run a new command with a given affinity mask:
- taskset mask command [arguments]
- You can also retrieve the CPU affinity of an existing task:
- taskset -p pid
- Or set it:
- taskset -p mask pid
PERMISSIONSA user can change the CPU affinity of a process belonging to the same user. A user must possess CAP_SYS_NICE to change the CPU affinity of a process belonging to another user. A user can retrieve the affinity mask of any process.
SEE ALSOchrt(1), nice(1), renice(1), sched_setaffinity(2), sched_getaffinity(2)
See sched_setscheduler(2) for a description of the Linux scheduling scheme.