Ubuntu Manpage: cset-set - manage sets of cpus

NAME

       cset-set - manage sets of cpus

SYNOPSIS

       cset [cset options] set [set options] [args]
       cset set --help
       cset set
       cset set --recurse
       cset set --list myset
       cset set myset
       cset set --recurse --list myset
       cset set --cpu 2-5 --mem 0 --set newset
       cset set --cpu 2-5 newset
       cset set --cpu 1,2,5-7 another_set
       cset set --destroy newset
       cset set --destroy /mygroup_sets/my_set

OPTIONS

       -h, --help
           prints the list of options for this command

       -l, --list
           list the named cpuset(s); if -a is used, will list members of named cpuset; if -r is
           used, will list recursively

       -c CPUSPEC, --cpu=CPUSPEC
           create or modify cpuset in the specified cpuset with CPUSPEC specification

       -m MEMSPEC, --mem=MEMSPEC
           specify which memory nodes to assign to the created or modified cpuset

       -d, --destroy
           destroy specified cpuset

       -s CPUSET, --set=CPUSET
           specify cpuset name to be acted on

       -r, --recurse
           do recursive listing, for use with --list

       -v, --verbose
           prints more detailed output, for the set command, using this flag will not chop
           listing to fit in 80 columns

       --cpu_exclusive
           mark this cpuset as owning its CPUs exclusively

       --mem_exclusive
           mark this cpuset as owning its MEMs exclusively

DESCRIPTION

This command is used to create, modify, and destroy cpusets. Cpusets form a tree-like
structure rooted at the root cpuset which always includes all system CPUs and all system
memory nodes.

A cpuset is an organizational unit that defines a group of CPUs and a group of memory
nodes where a process or thread (i.e. task) is allowed to run on. For non-NUMA machines,
the memory node is always 0 (zero) and cannot be set to anything else. For NUMA machines,
the memory node can be set to a similar specification as the CPU definition and will tie
those memory nodes to that cpuset. You will usually want the memory nodes that belong to
the CPUs defined to be in the same cpuset.

A cpuset can have exclusive right to the CPUs defined in it. This means that only this
cpuset can own these CPUs. Similarly, a cpuset can have exclusive right to the memory
nodes defined in it. This means that only this cpuset can own these memory nodes.

Cpusets can be specified by name or by path; however, care should be taken when specifying
by name if the name is not unique. This tool will generally not let you do destructive
things to non-unique cpuset names.

Cpusets are uniquely specified by path. The path starts at where the cpusets filesystem is
mounted so you generally do not have to know where that is. For example, so specify a
cpuset that is called "two" which is a subset of "one" which in turn is a subset of the
root cpuset, use the path "/one/two" regardless of where the cpusets filesystem is
mounted.

When specifying CPUs, a so-called CPUSPEC is used. The CPUSPEC will accept a
comma-separated list of CPUs and inclusive range specifications. For example,
--cpu=1,3,5-7 will assign CPU1, CPU3, CPU5, CPU6, and CPU7 to the specified cpuset.

Note that cpusets follow certain rules. For example, children can only include CPUs that
the parents already have. If you do not follow those rules, the kernel cpuset subsystem
will not let you create that cpuset. For example, if you create a cpuset that contains
CPU3, and then attempt to create a child of that cpuset with a CPU other than 3, you will
get an error, and the cpuset will not be active. The error is somewhat cryptic in that it
is usually a "Permission denied" error.

Memory nodes are specified with a MEMSPEC in a similar way to the CPUSPEC. For example,
--mem=1,3-6 will assign MEM1, MEM3, MEM4, MEM5, and MEM6 to the specified cpuset.

Note that if you attempt to create or modify a cpuset with a memory node specification
that is not valid, you may get a cryptic error message, "No space left on device", and the
modification will not be allowed.

When you destroy a cpuset, then the tasks running in that set are moved to the parent of
that cpuset. If this is not what you want, then manually move those tasks to the cpuset of
your choice with the cset proc command (see cset proc --help for more information).

EXAMPLES
Create a cpuset with the default memory specification
# cset set --cpu=2,4,6-8 --set=new_set
This command creates a cpuset called "new_set" located off the root cpuset which holds
CPUS 2,4,6,7,8 and node 0 (interleaved) memory. Note that --set is optional, and you can
just specify the name for the new cpuset after all arguments.

Create a cpuset that specifies both CPUs and memory nodes
# cset set --cpu=3 --mem=3 /rad/set_one
Note that this command uses the full path method to specify the name of the new cpuset
"/rad/set_one". It also names the new cpuset implicitly (i.e. no --set option, although
you can use that if you want to). If the "set_one" name is unique, you can subsequently
refer to is just by that. Memory node 3 is assigned to this cpuset as well as CPU 3.

The above commands will create the new cpusets, or if they already exist, they will modify
them to the new specifications.

LICENSE

       Cpuset is licensed under the GNU GPL V2 only.

COPYRIGHT

       Copyright (c) 2008-2011 Novell Inc.

AUTHOR

       Written by Alex Tsariounov <alext@novell.com>.