NAME

SYNOPSIS

OPTIONS

--single

Singlify each output to a single CPU.

--taskset

Show CPU set strings in the format recognized by the taskset command-line program instead of hwloc-specific CPU set string format.

-v --verbose

Verbose messages.

-i <file>, --input <file>

Read topology from XML file <file> (instead of discovering the topology on the local machine). If <file> is "-", the standard input is used. XML support must have been compiled in to hwloc for this option to be usable.

-i <directory>, --input <directory>

Read topology from the chroot specified by <directory> (instead of discovering the topology on the local machine). This option is generally only available on Linux. The chroot was usually created by gathering another machine topology with hwloc-gather-topology.

-i <specification>, --input <specification>

Simulate a fake hierarchy (instead of discovering the topology on the local machine). If <specification> is "node:2 pu:3", the topology will contain two NUMA nodes with 3 processing units in each of them. The <specification> string must end with a number of PUs.

--if <format>, --input-format <format>

Enforce the input in the given format, among xml, fsroot and synthetic.

--ignore <type>

Ignore all objects of type <type> in the topology.

--from <type>

Distribute starting from objects of the given type instead of from the top of the topology hierarchy, i.e. ignoring the structure given by objects above.

--to <type>

Distribute down to objects of the given type instead of down to the bottom of the topology hierarchy, i.e. ignoring the structure given by objects below. This may be useful if some latitude is desired for the binding, e.g. just bind several processes to each package without specifying a single core for each of them.

--at <type>

Distribute among objects of the given type. This is equivalent to specifying both --from and --to at the same time.

--reverse

Distribute by starting with the last objects first, and singlify CPU sets by keeping the last bit (instead of the first bit).

--restrict <cpuset>

Restrict the topology to the given cpuset.

--whole-system

Do not consider administration limitations.

--version

Report version and exit.

DESCRIPTION

This can e.g. be used to distribute a set of processes hierarchically according to the topology of a machine. These masks can be used with hwloc-bind(1).

NOTE: It is highly recommended that you read the hwloc(7) overview page before reading this man page. Most of the concepts described in hwloc(7) directly apply to the hwloc-bind utility.

EXAMPLES

If 4 processes have to be distributed across a machine, their CPU masks may be obtained with:

$ hwloc-distrib 4 0x0000000f 0x00000f00 0x000000f0 0x0000f000

To distribute only among the second package, the topology should be restricted:

$ hwloc-distrib --restrict $(hwloc-calc package:1) 4 0x00000010 0x00000020 0x00000040 0x00000080

To get a single processor of each CPU masks (prevent migration in case of binding)

$ hwloc-distrib 4 --single 0x00000001 0x00000100 0x00000010 0x00001000

Each output line may be converted independently with hwloc-calc:

$ hwloc-distrib 4 --single | hwloc-calc --taskset 0x1 0x100 0x10 0x1000

To convert the output into a list of processors that may be passed to dplace -c inside a mpirun command line:

$ hwloc-distrib 4 --single | xargs hwloc-calc --pulist 0,8,4,16

RETURN VALUE

hwloc-distrib will return nonzero if any kind of error occurs, such as (but not limited to) failure to parse the command line.

SEE ALSO