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HWLOC-DISTANCES(1) hwloc HWLOC-DISTANCES(1)
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)
1.11.1 October 15, 2015 HWLOC-DISTANCES(1)