taskset — retrieve or set a processes's CPU affinity
taskset [options] [ mask |
list ] [ pid | command [arg...] ]
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 are typically given in hexadecimal. For example,
0x00000001is processor #0
0x00000003is processors #0 and #1
0xFFFFFFFFis all processors (#0 through #31)
When taskset returns, it is guaranteed that the given program has been scheduled to a legal CPU.
−p,−−pidoperate on an existing PID and not launch a new task
−c,−−cpu−listspecifiy 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,−−helpdisplay usage information and exit
−V,−−versionoutput version information and exit
taskset [mask] -- [command] [arguments]
taskset -p [pid]
taskset -p [mask] [pid]
A user must possess CAP_SYS_NICE to change the CPU affinity of
a process. Any user can retrieve the affinity mask.
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.
chrt(1), nice(1), renice(1), sched_setaffinity(2), sched_getaffinity(2)
See sched_setscheduler(2) for a description of the Linux scheduling scheme.
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taskset(1) manpage Copyright (C) 2004 Robert Love This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system, including intermediate and printed output. This manual is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this manual; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. 2002-05-11 Robert Love <rmltech9.net> Initial version |