taskset set or retrieve a process CPU affinity

超、凢脫俗 2023-02-09 13:12 14阅读 0赞

## SYNOPSIS         [top][] ##

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.

--cpu-list 0-10:2  
                       is processors \#0, \#2, \#4, \#6, \#8 and \#10. The suffix  
                       ":N" specifies stride in the range, for example  
                       0-10:3 is interpreted as 0,3,6,9 list.

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
           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         [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),
           sched_setaffinity(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
           MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

## AVAILABILITY         [top][] ##

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

## 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 
           〈https://www.kernel.org/pub/linux/utils/util-linux/〉.  If you have a
           bug report for this manual page, send it to
           util-linux@vger.kernel.org.  This page was obtained from the
           project's upstream Git repository
           〈git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git〉 on
           2020-05-16.  (At that time, the date of the most recent commit that
           was found in the repository was 2020-05-15.)  If you discover any
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           (which is not part of the original manual page), send a mail to
           man-pages@man7.org

[top]: http://man7.org/linux/man-pages/man1/taskset.1.html#top_of_page