TASKSET(1) manual page
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taskset - retrieve or set a process’s CPU affinity
taskset [options] mask command [arg]...
taskset [options] -p [mask] pid
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.
- -a, --all-tasks
- Set or retrieve
the CPU affinity of all the tasks (threads) for a given PID.
- -p, --pid
- Operate
on an existing PID and do not launch a new task.
- -c, --cpu-list
- Specify a numerical
list of processors instead of a bitmask. The numbers are separated by commas
and may include ranges. For example: 0,5,7,9-11.
- -h, --help
- Display help text
and exit.
- -V, --version
- Display version information and exit.
- 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
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.
Written
by Robert M. Love.
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.
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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