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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
   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
   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
          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

   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_setaffinity(2), sched_getaffinity(2)

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

AUTHOR

   Written by Robert M. Love.

COPYRIGHT

   Copyright  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 PARTICULAR PURPOSE.

AVAILABILITY

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



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