cset(1) manage cpusets functions in the Linux kernel


cset [--version | --help | --tohex]
cset [help <command> | <command> --help]
cset [cset options] <command> [command options] [args]


In general, you need to have root permissions to run cset. The tool mounts the cpusets filesystem and manipulates it. Non-root users do not have permission for these actions.

Cset is a Python application to make using the cpusets facilities in the Linux kernel easier. The actual included command is called cset and it allows manipulation of cpusets on the system and provides higher level functions such as implementation and control of a basic cpu shielding setup.

Typical uses of cset include

Setting up and managing a simple shielded CPU environment

The concept of shielded cpus is that a certain number of cpus are partitioned off on the system and only processes that are of interest are run on these cpus (i.e., inside the shield).

For a simple shielded configuration, one typically uses three cpusets: the root set, a system set and a user set. Cset includes a super command that implements this strategy and lets you easily manage it. See cset-shield(1) for more details.

Setting up and managing a complex shielding environment

Shielding can be more complex of course where concepts such as priority cpusets and intersecting cpuset can be used. You can use cset to help manage this type of shielding as well. You will need to use the cset-set(1) and cset-proc(1) subcommands directly to do that.

Managing cpusets on the system

The cset subcommand cset-set(1) allows you to create and destroy arbitrary cpusets on the system and assign arbitrary cpus and memory nodes to them. The cpusets so created have to follow the Linux kernel cpuset rules. See the cset-set(1) subcommand for more details.

Managing processes that run on various system cpusets

The cset subcommand cset-proc(1) allows you to manage processes running on various cpusets created on the system. You can exec new processes in specific cpusets and move tasks around existing cpusets. See the cset-proc(1) subcommand for more details.


The following generic option flags are available. Additional options are available per-command, and documented in the command-specific documentation.

cset --version

Display version information and exits.

cset --help

Prints the synopsis and a list of all commands.

cset --log <filename>

Creates a log file for the current run. All manner of useful information is stored in this file. This is usually used to debug cset when things don't go as planned.

cset --machine

Makes cset output information for all operations in a format that is machine readable (i.e. easy to parse).

cset --tohex <CPUSPEC>

Converts a CPUSPEC (see cset-set(1) for definition) to a hexadecimal number and outputs it. Useful for setting IRQ stub affinity to a cpuset definition.


The cset commands are divided into groups, according to the primary purpose of those commands. Following is a short description of each command. A more detailed description is available in individual command manpages. Those manpages are named cset-<command>(1). The first command, help, is especially useful as it prints out a long summary of what a particular command does.

cset help command

print out a lengthy summary of how the specified subcommand works

cset command --help

print out an extended synopsis of the specified subcommand

cset shield

supercommand to set up and manage basic shielding (see cset-shield(1))

cset set

create, modify and destroy cpusets (see cset-set(1))

cset proc

create and manage processes within cpusets (see cset-proc(1))


To create a persistent cpuset setup, i.e. one that survives a reboot, you need to create the file /etc/init.d/cset. This distribuition of cset includes an example cset init.d file found in /usr/share/doc/pacakges/cpuset which is called cset.init.d. You will need to alter the file to your specifications and copy it to be the file /etc/init.d/cset. See the comments in that file for more details.


If used, the init.d script /etc/init.d/cset starts and stops a cpuset configuration on boot and poweroff.

Cpuset uses a configuration file if present on the system. The file is /etc/cset.conf and may contain the following options.

mountpoint = <directory_name>

Specify the mountpoint where the cpuset filesystem is to be mounted. By default this is /cpusets; however, some people prefer to mount this in the more traditional /dev/cpusets.


Cpuset is licensed under the GNU GPL V2 only.


Copyright (c) 2008-2011 Novell Inc.


Written by Alex Tsariounov <[email protected]>

Some substrate code and ideas were taken from the excellent Stacked GIT (stgit) v0.13 (see http://gna.org/projects/stgit and http://www.procode.org/stgit). Stacked GIT is under GPL V2 or later.