NAME

       hwloc-distances - Displays distance matrices

SYNOPSIS

       hwloc-distances [options]

OPTIONS

       -l --logical
              Display hwloc logical indexes (default) instead of physical/OS indexes.

       -p --physical
              Display OS/physical indexes instead of hwloc logical indexes.

       -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.

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

       --whole-system
              Do not consider administration limitations.

       -v --verbose
              Verbose messages.

       --version
              Report version and exit.

DESCRIPTION

       hwloc-distances  displays  also  distance matrices attached to the topology.  The value in
       the i-th row and j-th column is the distance from object #i to object #j.

       Unless defined by the user, matrices currently always contain relative  latencies  between
       NUMA   nodes  (which  may  or  may  not  be  accurate).   See  the  definition  of  struct
       hwloc_distances_s in include/hwloc.h or the documentation for details.

       These latencies are normalized to the latency of a local (non-NUMA) access.  Hence 3.5  in
       row  #i column #j means that the latency from cores in NUMA node #i to memory in NUMA node
       #j is 3.5 higher than the latency from cores  to  their  local  memory.   A  breadth-first
       traversal  of  the  topology  is  performed  starting  from  the root to find all distance
       matrices.

       NOTE: lstopo may also display distance matrices in its verbose  textual  output.   However
       lstopo  only  prints  matrices  that  cover the entire topology while hwloc-distances also
       displays matrices that ignore part of the topology.

EXAMPLES

       On a quad-package opteron machine:

           $ hwloc-distances
           Latency matrix between 4 NUMANodes (depth 2) by logical indexes:
             index     0     1     2     3
                 0 1.000 1.600 2.200 2.200
                 1 1.600 1.000 2.200 2.200
                 2 2.200 2.200 1.000 1.600
                 3 2.200 2.200 1.600 1.000

RETURN VALUE

       Upon successful execution, hwloc-distances returns 0.

       hwloc-distances 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), lstopo(1)