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



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

SYNOPSIS
       taskset [options] [mask | list ] [pid | command [arg]...]

DESCRIPTION
       taskset	is used to set or retrieve the CPU affinity of a running pro-
       cess given its PID or to launch a new COMMAND with a given CPU  affin-
       ity.  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 prac-
       tical 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,

       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
	      specifiy 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	 pro-
       cess.  Any user can retrieve the affinity mask.

AUTHOR
       Written by Robert M. Love.

REPORTING BUGS
       Report bugs to .

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 FITNESS FOR A PARTICU-
       LAR PURPOSE.

SEE ALSO
       chrt(1),	 nice(1),  renice(1),  sched_setaffinity(2),  sched_getaffin-
       ity(2)

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



schedutils			   Apr 2003			   TASKSET(1)

UNIX/Linux commands referenced on this page:

1. as
2. last
3. more
4. display
5. free