HWLOC-CALC(1) hwloc HWLOC-CALC(1)NAMEhwloc-calc - Operate on cpu mask strings and objects
SYNOPSIShwloc-calc [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.
OPTIONS-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 out‐
put.
--lo --logical-output
Use logical indexes instead of physical/OS indexes for output
(default, except for cpusets which are always physical).
-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.
-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.
-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 hierar‐
chical indexes with respect to <type1>, <type2>, etc. For
instance, if socket.core is given, the output would be
Socket:1.Core:2 Socket:2.Core:3 if the input contains the
third core of the second socket and the fourth core of the
third socket.
--largest Report (in a human readable format) the list of largest
objects which exactly include all input objects. 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.
--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.
--restrict <cpuset>
Restrict the topology to the given cpuset.
-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 topol‐
ogy on the local machine). If <specification> is "node:2
pu:3", the topology will contain two NUMA nodes with 3 pro‐
cessing 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.
-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.
DESCRIPTIONhwloc-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).
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 stan‐
dard 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. For
instance, it means that 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 socket:
$ hwloc-calc socket:1
0x000000f0
To display the (physical) CPU mask corresponding to the third socket,
excluding its even numbered logical processors:
$ hwloc-calc socket:2 ~PU:even
0x00000c00
To combine two (physical) CPU masks:
$ hwloc-calc 0x0000ffff 0xff000000
0xff00ffff
To display the list of logical numbers of processors included in the
second socket:
$ hwloc-calc--intersect PU socket: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 --inter‐
sect PU machine:0`
$ 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 display the physical index of a processor given by its logical
index:
$ hwloc-calc PU:2 --physical-output --intersect PU
3
To display the set of CPUs near network interface eth0:
$ hwloc-calc os=eth0
0x00005555
To display the indexes of sockets near PCI device whose bus ID is
0000:01:02.0:
$ hwloc-calc pci=0000:01:02.0 --intersect Socket
1
To display the list of per-socket cores that intersect the input:
$ hwloc-calc 0x00003c00 --hierarchical socket.core
Socket:2.Core:1 Socket:3.Core:0
To display the (physical) CPU mask of the entire topology except the
third socket:
$ hwloc-calc all ~socket: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-socket
2-core machine:
$ hwloc-calc core:0 --largest
Core:0
$ hwloc-calc core:0-1 --largest
Socket:0
$ hwloc-calc core:4-7 --largest
NUMANode:1
$ hwloc-calc core:2-6 --largest
Socket:1 Socket:2 Core:6
$ hwloc-calc socket:2 --largest
Socket:2
$ hwloc-calc socket:2-3 --largest
NUMANode:1
To get the set of first threads of all cores:
$ hwloc-calc core:all.pu:0
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 machine:0`
$ echo $OMP_NUM_THREADS
4
$ export GOMP_CPU_AFFINITY=`hwloc-calc --physical-output --inter‐
sect PU core:all.pu:0`
$ echo $GOMP_CPU_AFFINITY
0,2,1,3
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 ALSOhwloc(7), lstopo(1), hwloc-info(1), hwloc-gather-topology(1)1.7 Apr 07, 2013 HWLOC-CALC(1)
