Provided by: hwloc-nox_2.8.0-1_amd64 
NAME
hwloc-calc - Operate on cpu mask strings and objects
SYNOPSIS
hwloc-calc [topology options] [options] <location1> [<location2> [...] ]
Note that hwloc(7) provides a detailed explanation of the hwloc system and of valid
<location> formats; it should be read before reading this man page.
TOPOLOGY OPTIONS
All topology options must be given before all other options.
--no-smt, --no-smt=<N>
Only keep the first PU per core in the input locations. If <N> is specified,
keep the <N>-th instead, if any. PUs are ordered by physical index during this
filtering.
--cpukind <n>
--cpukind <infoname>=<infovalue> Only keep PUs whose CPU kind match. Either a
single CPU kind is specified as an index, or the info name/value keypair will
select matching kinds.
When specified by index, it corresponds to hwloc ranking of CPU kinds which
returns energy-efficient cores first, and high-performance power-hungry cores
last. The full list of CPU kinds may be seen with lstopo --cpukinds.
--restrict <cpuset>
Restrict the topology to the given cpuset.
--restrict nodeset=<nodeset>
Restrict the topology to the given nodeset, unless --restrict-flags specifies
something different.
--restrict-flags <flags>
Enforce flags when restricting the topology. Flags may be given as numeric
values or as a comma-separated list of flag names that are passed to
hwloc_topology_restrict(). Those names may be substrings of actual flag names
as long as a single one matches, for instance bynodeset,memless. The default is
0 (or none).
--disallowed
Include objects disallowed by administrative limitations.
-i <path>, --input <path>
Read the topology from <path> instead of discovering the topology of the local
machine.
If <path> is a file and XML support has been compiled in hwloc, it may be a XML
file exported by a previous hwloc program. If <path> is "-", the standard input
may be used as a XML file.
On Linux, <path> may be a directory containing the topology files gathered from
another machine topology with hwloc-gather-topology.
On x86, <path> may be a directory containing a cpuid dump gathered with hwloc-
gather-cpuid.
When the archivemount program is available, <path> may also be a tarball
containing such Linux or x86 topology files.
-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, cpuid and synthetic.
OPTIONS
All these options must be given after all topology options above.
-p --physical
Use OS/physical indexes instead of logical indexes for both input and output.
-l --logical
Use logical indexes instead of physical/OS indexes for both input and output
(default).
--pi --physical-input
Use OS/physical indexes instead of logical indexes for input.
--li --logical-input
Use logical indexes instead of physical/OS indexes for input (default).
--po --physical-output
Use OS/physical indexes instead of logical indexes for output.
--lo --logical-output
Use logical indexes instead of physical/OS indexes for output (default, except
for cpusets which are always physical).
-n --nodeset
Interpret both input and output sets as nodesets instead of CPU sets. See
--nodeset-output and --nodeset-input below for details.
--no --nodeset-output
Report nodesets instead of CPU sets. This output is more precise than the
default CPU set output when memory locality matters because it properly
describes CPU-less NUMA nodes, as well as NUMA-nodes that are local to multiple
CPUs.
--ni --nodeset-input
Interpret input sets as nodesets instead of CPU sets.
-N --number-of <type|depth>
Report the number of objects of the given type or depth that intersect the CPU
set. This is convenient for finding how many cores, NUMA nodes or PUs are
available in a machine.
When combined with --nodeset or --nodeset-output, the nodeset is considered
instead of the CPU set for finding matching objects. This is useful when
reporting the output as a number or set of NUMA nodes.
-I --intersect <type|depth>
Find the list of objects of the given type or depth that intersect the CPU set
and report the comma-separated list of their indexes instead of the cpu mask
string. This may be used for determining the list of objects above or below the
input objects.
When combined with --physical, the list is convenient to pass to external tools
such as taskset or numactl --physcpubind or --membind. This is different from
--largest since the latter requires that all reported objects are strictly
included inside the input objects.
When combined with --nodeset or --nodeset-output, the nodeset is considered
instead of the CPU set for finding matching objects. This is useful when
reporting the output as a number or set of NUMA nodes.
-H --hierarchical <type1>.<type2>...
Find the list of objects of type <type2> that intersect the CPU set and report
the space-separated list of their hierarchical indexes with respect to <type1>,
<type2>, etc. For instance, if package.core is given, the output would be
Package:1.Core:2 Package:2.Core:3 if the input contains the third core of the
second package and the fourth core of the third package.
Only normal CPU-side object types may be used. NUMA nodes cannot.
--largest Report (in a human readable format) the list of largest objects which exactly
include all input objects (by looking at their CPU sets). None of these output
objects intersect each other, and the sum of them is exactly equivalent to the
input. No largest object is included in the input This is different from
--intersect where reported objects may not be strictly included in the input.
--local-memory
Report the list of NUMA nodes that are local to the input objects.
This option is similar to -I numa but the way nodes are selected is different:
The selection performed by --local-memory may be precisely configured with
--local-memory-flags, while -I numa just selects all nodes that are somehow
local to any of the input objects.
--local-memory-flags
Change the flags used to select local NUMA nodes. Flags may be given as numeric
values or as a comma-separated list of flag names that are passed to
hwloc_get_local_numanode_objs(). Those names may be substrings of actual flag
names as long as a single one matches. The default is 3 (or smaller,larger)
which means NUMA nodes are displayed if their locality either contains or is
contained in the locality of the given object.
This option enables --local-memory.
--best-memattr <name>
Enable the listing of local memory nodes with --local-memory, but only display
the local node that has the best value for the memory attribute given by <name>
(or as an index).
If the memory attribute values depend on the initiator, the hwloc-calc input
objects are used as the initiator.
Standard attribute names are Capacity, Locality, Bandwidth, and Latency. All
existing attributes in the current topology may be listed with
$ lstopo --memattrs
--sep <sep>
Change the field separator in the output. By default, a space is used to
separate output objects (for instance when --hierarchical or --largest is given)
while a comma is used to separate indexes (for instance when --intersect is
given).
--single Singlify the output to a single CPU.
--taskset Display CPU set strings in the format recognized by the taskset command-line
program instead of hwloc-specific CPU set string format. This option has no
impact on the format of input CPU set strings, both formats are always accepted.
-q --quiet
Hide non-fatal error messages. It mostly includes locations pointing to non-
existing objects.
-v --verbose
Verbose output.
--version Report version and exit.
-h --help Display help message and exit.
DESCRIPTION
hwloc-calc generates and manipulates CPU mask strings or objects. Both input and output
may be either objects (with physical or logical indexes), CPU lists (with physical or
logical indexes), or CPU mask strings (always physically indexed). Input location
specification is described in hwloc(7).
If objects or CPU mask strings are given on the command-line, they are combined and a
single output is printed. If no object or CPU mask strings are given on the command-line,
the program will read the standard input. It will combine multiple objects or CPU mask
strings that are given on the same line of the standard input line with spaces as
separators. Different input lines will be processed separately.
Command-line arguments and options are processed in order. First topology configuration
options should be given. Then, for instance, changing the type of input indexes with --li
or changing the input topology with -i only affects the processing the following
arguments.
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-
calc utility.
EXAMPLES
hwloc-calc's operation is best described through several examples.
To display the (physical) CPU mask corresponding to the second package:
$ hwloc-calc package:1
0x000000f0
To display the (physical) CPU mask corresponding to the third pacakge, excluding its even
numbered logical processors:
$ hwloc-calc package:2 ~PU:even
0x00000c00
To convert a cpu mask to human-readable output, the -H option can be used to emit a space-
delimited list of locations:
$ echo 0x000000f0 | hwloc-calc -H package.core
Package:1.Core1 Package:1.Core:1 Package:1.Core:2 Package:1.Core:3
To use some other character (e.g., a comma) instead of spaces in output, use the --sep
option:
$ echo 0x000000f0 | hwloc-calc -H package.core --sep ,
Package:1.Core1,Package:1.Core:1,Package:1.Core:2,Package:1.Core:3
To combine two (physical) CPU masks:
$ hwloc-calc 0x0000ffff 0xff000000
0xff00ffff
To display the list of logical numbers of processors included in the second package:
$ hwloc-calc --intersect PU package:1
4,5,6,7
To bind GNU OpenMP threads logically over the whole machine, we need to use physical
number output instead:
$ export GOMP_CPU_AFFINITY=`hwloc-calc --physical-output --intersect PU all`
$ echo $GOMP_CPU_AFFINITY
0,4,1,5,2,6,3,7
To display the list of NUMA nodes, by physical indexes, that intersect a given (physical)
CPU mask:
$ hwloc-calc --physical --intersect NUMAnode 0xf0f0f0f0
0,2
To find how many cores are in the second CPU kind (those cores are likely higher-
performance and more power-hungry than cores of the first kind):
$ hwloc-calc --cpukind 1 -N core all
4
To display the list of NUMA nodes, by physical indexes, whose locality is exactly equal to
a Package:
$ hwloc-calc --local-memory-flags 0 pack:1
4,7
To display the best-capacity NUMA node, by physical indexe, whose locality is exactly
equal to a Package:
$ hwloc-calc --local-memory-flags 0 --best-memattr capacity pack:1
4
Converting object logical indexes (default) from/to physical/OS indexes may be performed
with --intersect combined with either --physical-output (logical to physical conversion)
or --physical-input (physical to logical):
$ hwloc-calc --physical-output PU:2 --intersect PU
3
$ hwloc-calc --physical-input PU:3 --intersect PU
2
One should add --nodeset when converting indexes of memory objects to make sure a single
NUMA node index is returned on platforms with heterogeneous memory:
$ hwloc-calc --nodeset --physical-output node:2 --intersect node
3
$ hwloc-calc --nodeset --physical-input node:3 --intersect node
2
To display the set of CPUs near network interface eth0:
$ hwloc-calc os=eth0
0x00005555
To display the indexes of packages near PCI device whose bus ID is 0000:01:02.0:
$ hwloc-calc pci=0000:01:02.0 --intersect Package
1
To display the list of per-package cores that intersect the input:
$ hwloc-calc 0x00003c00 --hierarchical package.core
Package:2.Core:1 Package:3.Core:0
To display the (physical) CPU mask of the entire topology except the third package:
$ hwloc-calc all ~package:3
0x0000f0ff
To combine both physical and logical indexes as input:
$ hwloc-calc PU:2 --physical-input PU:3
0x0000000c
To synthetize a set of cores into largest objects on a 2-node 2-package 2-core machine:
$ hwloc-calc core:0 --largest
Core:0
$ hwloc-calc core:0-1 --largest
Package:0
$ hwloc-calc core:4-7 --largest
NUMANode:1
$ hwloc-calc core:2-6 --largest
Package:1 Package:2 Core:6
$ hwloc-calc pack:2 --largest
Package:2
$ hwloc-calc package:2-3 --largest
NUMANode:1
To get the set of first threads of all cores:
$ hwloc-calc core:all.pu:0
$ hwloc-calc --no-smt all
This can also be very useful in order to make GNU OpenMP use exactly one thread per core,
and in logical core order:
$ export OMP_NUM_THREADS=`hwloc-calc --number-of core all`
$ echo $OMP_NUM_THREADS
4
$ export GOMP_CPU_AFFINITY=`hwloc-calc --physical-output --intersect PU --no-smt all`
$ echo $GOMP_CPU_AFFINITY
0,2,1,3
To export bitmask in a format that is acceptable by the resctrl Linux subsystem (for
configuring cache partitioning, etc), apply a sed regexp to the output of hwloc-calc:
$ hwloc-calc pack:all.core:7-9.pu:0
0x00000380,,0x00000380 <this format cannot be given to resctrl>
$ hwloc-calc pack:all.core:7-9.pu:0 | sed -e 's/0x//g' -e 's/,,/,0,/g' -e 's/,,/,0,/g'
00000380,0,00000380
# echo 00000380,0,00000380 > /sys/fs/resctrl/test/cpus
# cat /sys/fs/resctrl/test/cpus
00000000,00000380,00000000,00000380 <the modified bitmask was corrected parsed by
resctrl>
RETURN VALUE
Upon successful execution, hwloc-calc displays the (physical) CPU mask string, (physical
or logical) object list, or (physical or logical) object number list. The return value is
0.
hwloc-calc 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), hwloc-info(1)