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 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
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 © 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.
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/.