`taskset` Taskset Command

Overview

The taskset command displays or changes the CPU affinity mask for a running task, or starts a command after applying an affinity mask to the taskset process. It is intended for SMP configurations where tasks can be constrained to a subset of CPUs.

The mask argument is a decimal CPU affinity bit mask. Bit 0 selects CPU 0, bit 1 selects CPU 1, and so on. The command accepts masks greater than zero and less than 1 << CONFIG_SMP_NCPUS.

Configuration

Enable the application with CONFIG_SYSTEM_TASKSET. This option depends on CONFIG_SMP and CONFIG_SYSTEM_SYSTEM.

The program name, task priority, and stack size are controlled by:

CONFIG_SYSTEM_TASKSET_PROGNAME
CONFIG_SYSTEM_TASKSET_PRIORITY
CONFIG_SYSTEM_TASKSET_STACKSIZE

Usage

taskset <mask> <command> [args ...]
taskset -p [mask] <pid>
taskset -h

Forms

taskset <mask> <command> [args ...]: Applies mask to the taskset process and then runs command with any remaining arguments through system().
taskset -p <pid>: Prints the current CPU affinity mask for pid.
taskset -p <mask> <pid>: Sets the CPU affinity mask for pid and then prints the task’s current mask.
taskset -h: Prints command usage.

Examples

Show the current affinity mask for task ID 4:

nsh> taskset -p 4
pid 4's current affinity mask: 0x2

Set task ID 4 to affinity mask 3 and print the resulting mask:

nsh> taskset -p 3 4
pid 4's current affinity mask: 0x3

Start busyloop after applying affinity mask 1 to the command process:

nsh> taskset 1 busyloop &

Notes

The command reports scheduler affinity errors on standard error. The exact set of valid mask values depends on CONFIG_SMP_NCPUS for the target configuration.

taskset Taskset Command