taskset

Set process CPU affinity

TLDR

Show which CPUs a running process is allowed to use

$ taskset --pid --cpu-list [pid]

Pin a running process to one CPU

$ taskset --pid --cpu-list [2] [pid]

Pin every thread of the process, not just the main one

$ taskset --all-tasks --pid --cpu-list [0-3] [pid]

Launch a command pinned to a single CPU

$ taskset --cpu-list [0] [command]

Launch a command pinned to a range of CPUs

$ taskset --cpu-list [0-3] [command]

Launch a command pinned to a non-contiguous set

$ taskset --cpu-list [0,2,4] [command]

Use a hexadecimal mask instead of a list

$ taskset [0x3] [command]

Read a process's affinity as a mask

$ taskset --pid [pid]

SYNOPSIS

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

taskset retrieves or sets a process's CPU affinity, which controls which CPUs the process can run on. CPU affinity can be specified as a bitmask or a comma-separated list of CPU IDs.This is useful for performance tuning, isolating processes to specific cores, or testing how software behaves on limited CPU resources.

PARAMETERS

-p, --pid

Operate on an existing PID

-c, --cpu-list

Specify CPUs as a list instead of a bitmask

-a, --all-tasks

Set/get affinity of all tasks (threads)

-h, --help

Display help information

-V, --version

Display version information

INSTALL

sudo apt install util-linux

sudo dnf install util-linux

sudo pacman -S util-linux

sudo apk add util-linux-misc

sudo zypper install util-linux

brew install util-linux

nix profile install nixpkgs#util-linux

CAVEATS

CPU IDs start at 0. Setting affinity may not improve performance and can hurt it if done incorrectly. The kernel may still migrate processes for load balancing unless CPU isolation is configured. The CPU list supports stride syntax (e.g. 0-10:2 means CPUs 0,2,4,6,8,10). Part of the util-linux package.