taskset - retrieve or set a process's CPU affinity
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
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,
- is processor #0
- is processors #0 and #1
- is all processors (#0 through #31).
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
- -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:
- -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
- 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
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.
for a description of the Linux scheduling
The taskset command is part of the util-linux package and is available from