taskset(1)



TASKSET(1)                       User Commands                      TASKSET(1)

NAME
       taskset - set or retrieve a process's CPU affinity

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

DESCRIPTION
       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 practi-
       cal for performance reasons.  Therefore, forcing a specific CPU  affin-
       ity 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 corre-
       sponding  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 example,

           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
       -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 bit-
              mask.  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
       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

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

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

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 MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

AVAILABILITY
       The  taskset command is part of the util-linux package and is available
       from https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                        August 2014                       TASKSET(1)

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