taskset - Unix, Linux Command

NAME

taskset - retrieve or set a processes’s CPU affinity

SYNOPSIS

taskset [options] [mask | list ] [pid | command [arg]...]

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,

Tag	Description
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

Tag	Description
-p, --pid
	operate on an existing PID and not launch a new task
-c, --cpu-list
	specifiy 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

Tag	Description
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.

REPORTING BUGS

Report bugs to <[email protected]>.