HWLOC-DISTANCES(1) hwloc HWLOC-DISTANCES(1)NAMEhwloc-distances - Displays distance matrices
SYNOPSIShwloc-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.
DESCRIPTIONhwloc-distances displays also distance matrices attached to the topol‐
ogy. 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 ALSOhwloc(7), lstopo(1)1.11.1 Oct 15, 2015 HWLOC-DISTANCES(1)
