TASKSET(1)                      User Commands                     TASKSET(1)

NAME         top

       taskset - set or retrieve a process's CPU affinity

SYNOPSIS         top

       taskset [options] mask command [argument...]
       taskset [options] -p [mask] pid

DESCRIPTION         top

       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 may be specified in hexadecimal (with or without
       a leading "0x"), or as a CPU list with the --cpu-list option.  For

           0x00000001  is processor #0,

           0x00000003  is processors #0 and #1,

           0xFFFFFFFF  is processors #0 through #31,

           32          is processors #1, #4, and #5,

           --cpu-list 0-2,6
                       is processors #0, #1, #2, and #6.

       When taskset returns, it is guaranteed that the given program has
       been scheduled to a legal CPU.

OPTIONS         top

       -a, --all-tasks
              Set or retrieve the CPU affinity of all the tasks (threads)
              for a given PID.

       -c, --cpu-list
              Interpret mask as numerical list of processors instead of a
              bitmask.  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.

USAGE         top

       The default behavior is to run a new command with a given affinity
              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

PERMISSIONS         top

       A 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 ALSO         top

       chrt(1), nice(1), renice(1), sched_getaffinity(2),

       See sched(7) for a description of the Linux scheduling scheme.

AUTHOR         top

       Written by Robert M. Love.

COPYRIGHT         top

       Copyright © 2004 Robert M. Love.  This is free software; see the
       source for copying conditions.  There is NO warranty; not even for

AVAILABILITY         top

       The taskset command is part of the util-linux package and is
       available from

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨⟩.  If you have a
       bug report for this manual page, send it to  This page was obtained from the
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util-linux                       August 2014                      TASKSET(1)