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)

1.11.9                                            Jan 18, 2018                                HWLOC-DISTANCES(1)