Section: User Commands (1)
Updated: April 2003
taskset [options] mask 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,
- is processor #0:
- is processors #0 and #1:
- is all processors (#0 through #31).:
- -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 masktaskset mask command [arguments]
- You can also retrieve the CPU affinity of an existing tasktaskset -p pid
- Or set ittaskset -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.
Copyright © 2004 Robert M. Love
The taskset command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.