Provided by: hwloc-nox_1.3.1-1_i386 bug

NAME

       hwloc-distrib - Build a number of cpu masks distributed on the system

SYNOPSIS

       hwloc-distrib [options] <integer>

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 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.

       --top <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  on  sockets
              and not to precise cores or caches.

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

       --restrict <cpuset>
              Restrict the topology to the given cpuset.

       --version
              Report version and exit.

DESCRIPTION

       hwloc-distrib generates a  series  of  CPU  masks  corresponding  to  a
       distribution  of  a  given  number of elements over the topology of the
       machine. The distribution is done  recursively  from  the  top  of  the
       hierarchy  (or  from  the level specified by option --from) down to the
       bottom of the hierarchy (or down to the level specified by option --to,
       or until only one element remains), splitting the number of elements at
       each encountered hierarchy level not ignored by options --ignore.

       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

       hwloc-distrib's operation is best described through several 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 socket, the topology should be
       restricted:

           $ hwloc-distrib --restrict $(hwloc-calc socket: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

       Upon successful execution, hwloc-distrib displays one or more CPU  mask
       strings.  The return value is 0.

       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

       hwloc(7), hwloc-gather-topology(1)