HWLOC-BIND(1) hwloc HWLOC-BIND(1)
NAME
hwloc-bind - Launch a command that is bound to specific processors
and/or memory, or consult the binding of an existing program
SYNOPSIS
hwloc-bind [topology options] [options] <location1> [<location2> [...]
] [--] <command> ...
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 before binding. If <N> is
specified, keep the <N>-th instead, if any. PUs are ordered
by physical index during this filtering.
--restrict <cpuset>
Restrict the topology to the given cpuset.
--restrict nodeset=<nodeset>
Restrict the topology to the given nodeset, unless --re-
strict-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 de-
fault is 0 (or none).
--disallowed
Include objects disallowed by administrative limitations.
--best-memattr <name>
Select the best NUMA node among the given memory binding set
by looking at the memory attribute given by <name> (or as an
index).
If the memory attribute values depend on the initiator, the
CPU binding set is 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
--hbm Only take high bandwidth memory nodes (Intel Xeon Phi MCDRAM)
in account when looking for NUMA nodes in the input loca-
tions.
This option must be combined with NUMA node locations, such
as --hbm numa:1 for binding on the second HBM node. It may
also be written as hbm:1.
--no-hbm Ignore high bandwidth memory nodes (Intel Xeon Phi MCDRAM)
when looking for NUMA nodes in the input locations.
OPTIONS
All these options must be given after all topology options above.
--cpubind Use following arguments for CPU binding (default).
--membind Use following arguments for memory binding. If --mempolicy
is not also given, the default policy is bind.
--mempolicy <policy>
Change the memory binding policy. The available policies are
default, firsttouch, bind, interleave and nexttouch. This
option is only meaningful when an actual binding is also
given with --membind. If --membind is given without --mem-
policy, the default policy is bind.
--get Report the current bindings. The output is an opaque bitmask
that may be translated into objects with hwloc-calc (see EX-
AMPLES below).
When a command is given, the binding is displayed before exe-
cuting the command. When no command is given, the program ex-
its after displaying the current binding.
When combined with --membind, report the memory binding in-
stead of CPU binding.
No location may be given since no binding is performed.
--nodeset Report binding as a NUMA memory node set instead of a CPU set
if --get was given. This is useful for manipulating CPU-less
NUMA nodes since their cpuset is empty while their nodeset is
correct.
Also parse input bitmasks as nodesets instead of cpusets.
When this option is not passed, individual input bitmasks may
still be parsed as nodesets if they are prefixed with node-
set=.
-e --get-last-cpu-location
Report the last processors where the process ran. The output
is an opaque bitmask that may be translated into objects with
hwloc-calc (see EXAMPLES below).
Note that the result may already be outdated when reported
since the operating system may move the process to other pro-
cessors at any time according to the binding.
When a command is given, the last processors is displayed be-
fore executing the command. When no command is given, the
program exits after displaying the last processors.
This option cannot be combined with --membind.
No location may be given since no binding is performed.
--single Bind on a single CPU to prevent migration.
--strict Require strict binding.
--pid <pid>
Operate on pid <pid>
--tid <tid>
Operate on thread <tid> instead of on an entire process. The
feature is only supported on Linux for thread CPU binding, or
for reporting the last processor where the thread ran if -e
was also passed.
-p --physical
Interpret input locations with OS/physical indexes instead of
logical indexes. This option does not apply to the output,
see --get above.
-l --logical
Interpret input locations with logical indexes instead of
physical/OS indexes (default). This option does not apply to
the output, see --get above.
--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.
-f --force
Launch the executable even if binding failed.
-q --quiet
Hide non-fatal error messages. It includes locations point-
ing to non-existing objects, as well as failure to bind.
This is usually useful in addition to --force.
-v --verbose
Verbose output.
--version Report version and exit.
-h --help Display help message and exit.
DESCRIPTION
hwloc-bind execs an executable (with optional command line arguments)
that is bound to the specified location (or list of locations). Loca-
tion specification is described in hwloc(7). Upon successful execu-
tion, hwloc-bind simply sets bindings and then execs the executable
over itself.
If a bitmask location is given with prefix nodeset=, then it is consid-
ered a nodeset instead of a CPU set. See also --nodeset.
If multiple locations are given, they are combined in the sense that
the binding will be wider. The process will be allowed to run on every
location inside the combination.
The list of input locations may be explicitly ended with "--".
If binding fails, or if the binding set is empty, and --force was not
given, hwloc-bind returns with an error instead of launching the exe-
cutable.
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-bind utility.
EXAMPLES
hwloc-bind's operation is best described through several examples.
More details about how locations are specified on the hwloc-bind com-
mand line are described in hwloc(7).
To run the echo command on the first logical processor of the second
package:
$ hwloc-bind package:1.pu:0 -- echo hello
which is exactly equivalent to the following line as long as there is
no ambiguity between hwloc-bind option names and the executed command
name:
$ hwloc-bind package:1.pu:0 echo hello
To bind the "echo" command to the first core of the second package and
the second core of the first package:
$ hwloc-bind package:1.core:0 package:0.core:1 -- echo hello
To bind on the first PU of all cores of the first package:
$ hwloc-bind package:0.core:all.pu:0 -- echo hello
$ hwloc-bind --no-smt package:0 -- echo hello
To bind on the memory node local to a PU with largest capacity:
$ hwloc-bind --best-memattr capacity --cpubind pu:23 --membind
pu:23 -- echo hello
To bind memory on the first high-bandwidth memory node on Intel Xeon
Phi:
$ hwloc-bind --membind hbm:0 -- echo hello
$ hwloc-bind --hbm --membind numa:0 -- echo hello
Note that binding the "echo" command to multiple processors is probably
meaningless (because "echo" is likely implemented as a single-threaded
application); these examples just serve to show what hwloc-bind can do.
To run on the first three packages on the second and third nodes:
$ hwloc-bind node:1-2.package:0:3 -- echo hello
which is also equivalent to:
$ hwloc-bind node:1-2.package:0-2 -- echo hello
Note that if you attempt to bind to objects that do not exist, hwloc-
bind will not warn unless -v was specified.
To run on processor with physical index 2 in package with physical in-
dex 1:
$ hwloc-bind --physical package:1.core:2 -- echo hello
To run on odd cores within even packages:
$ hwloc-bind package:even.core:odd -- echo hello
To run on the first package, except on its second and fifth cores:
$ hwloc-bind package:0 ~package:0.core:1 ~package:0.core:4 -- echo
hello
To run anywhere except on the first package:
$ hwloc-bind all ~package:0 -- echo hello
To run on a core near the network interface named eth0:
$ hwloc-bind os=eth0 -- echo hello
To run on a core near the PCI device whose bus ID is 0000:01:02.0:
$ hwloc-bind pci=0000:01:02.0 -- echo hello
To bind memory on second memory node and run on first node (when sup-
ported by the OS):
$ hwloc-bind --cpubind node:1 --membind node:0 -- echo hello
The --get option can report current bindings. This example shows nest-
ing hwloc-bind invocations to set a binding and then report it:
$ hwloc-bind node:1.package:2 -- hwloc-bind --get
0x00004444,0x44000000
hwloc-calc can also be used to convert cpu mask strings to human-read-
able package/core/PU strings; see the description of -H in hwloc-
calc(1) for more details. The following example binds to all the PUs
in a specific core, uses the --get option to retrieve where the process
was actually bound, and then uses hwloc-calc to display the resulting
cpu mask in space-delimited list of human-readable locations:
$ hwloc-bind package:1.core:2 -- hwloc-bind --get | hwloc-calc -H
package.core.pu
Package:1.Core:2.PU:0 Package:1.Core:2.PU:1
hwloc-calc may convert this output into actual objects, either with
logical or physical indexes:
$ hwloc-calc --physical -I pu `hwloc-bind --get`
26,30,34,38,42,46
$ hwloc-calc --logical -I pu `hwloc-bind --get` --sep " "
24 25 26 27 28 29
Locations may also be specified as a hex bit mask (typically generated
by hwloc-calc). For example:
$ hwloc-bind 0x00004444,0x44000000 -- echo hello
$ hwloc-bind `hwloc-calc node:1.package:2` -- echo hello
The current memory binding may also be reported:
$ hwloc-bind --membind node:1 --mempolicy interleave -- hwloc-bind
--get --membind
0x000000f0 (interleave)
HINT
If the graphics-enabled lstopo is available, use for instance
$ hwloc-bind core:2 -- lstopo --pid 0
to check what the result of your binding command actually is. lstopo
will graphically show where it is bound to by hwloc-bind.
RETURN VALUE
Upon successful execution, hwloc-bind execs the command over itself.
The return value is therefore whatever the return value of the command
is.
hwloc-bind will return nonzero if any kind of error occurs, such as
(but not limited to): failure to parse the command line, failure to re-
trieve process bindings, or lack of a command to execute.
SEE ALSO
hwloc(7), lstopo(1), hwloc-calc(1), hwloc-distrib(1)
2.9.0 Dec 14, 2022 HWLOC-BIND(1)
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