TASKSET(1)                                             Linux User's Manual                                            TASKSET(1)



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

SYNOPSIS
       taskset [options] mask command [arg]...
       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
       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 sys-
       tem.  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,

       0x00000001
              is processor #0

       0x00000003
              is processors #0 and #1

       0xFFFFFFFF
              is all processors (#0 through #31)

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

OPTIONS
       -p, --pid
              operate on an existing PID and not launch a new task

       -c, --cpu-list
              specify  a  numerical  list of processors instead of a bitmask.  The list may contain multiple items, separated by
              comma, and ranges.  For example, 0,5,7,9-11.

       -h, --help
              display usage information and exit

       -V, --version
              output version information 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 must possess CAP_SYS_NICE to change the CPU affinity of a process.  Any user can retrieve the affinity mask.

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 MERCHANTABILITY or FIT-
       NESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       chrt(1), nice(1), renice(1), sched_setaffinity(2), sched_getaffinity(2)

       See sched_setscheduler(2) for a description of the Linux scheduling scheme.

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



schedutils                                                  Apr 2003                                                  TASKSET(1)