NAME¶

hwloc-bind - Launch a command that is bound to specific processors and/or memory.

SYNOPSIS¶

hwloc-bind [options] <location1> [<location2> [...] ] [--] <command> ...

OPTIONS¶

See below for a description of valid <location> formats.

--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 replicate and nexttouch. This option is only meaningful when an actual binding is also given with --membind. If --membind is given without --mempolicy, the default policy is bind.

--get

Report the current bindings. When combined with --membind, report the memory binding instead of CPU binding.

--get-last-cpu-location

Report the last processors where the process ran. Note that the result may already be outdated when reported since the operating system may move the process to other processors at any time according to the binding. This option cannot be combined with --membind.

--single

Bind on a single CPU to prevent migration.

--strict

Require strict binding.

--pid <pid>

Operate on pid <pid>

-p --physical

take OS/physical indexes instead of logical indexes

-l --logical

take logical indexes instead of physical/OS indexes (default)

--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.

-v

Verbose output.

--version

Report version and exit.

DESCRIPTION¶

hwloc-bind execs an executable (with optional command line arguments) that is bound to the specified location (or list of locations). Upon successful execution, hwloc-bind simply sets bindings and then execs the executable over itself.

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 command line are described in hwloc(7).

To run the echo command on the first logical processor of the second socket:

hwloc-bind socket:1.pu:0 -- echo hello

which is exactly equivalent to

hwloc-bind socket:1.pu:0 echo hello

To bind the "echo" command to the first core of the second socket and the second core of the first socket:

hwloc-bind socket:1.core:0 socket:0.core:1 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 sockets on the second and third nodes:

hwloc-bind node:1-2.socket:0:3 echo hello

which is also equivalent to:

hwloc-bind node:1-2.socket: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 socket with physical index 1:

hwloc-bind --physical socket:1.core:2 echo hello

To run on odd cores within even sockets:

hwloc-bind socket:even.core:odd echo hello

To run on the first socket, except on its second and fifth cores:

hwloc-bind socket:0 ~socket:0.core:1 ~socket:0.core:4 echo hello

To run anywhere except on the first socket:

hwloc-bind all ~socket: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 supported by the OS):

hwloc-bind --cpubind node:1 --membind node:0 echo hello

The --get option can report current bindings. This example shows nesting hwloc-bind invocations to set a binding and then report it:

hwloc-bind node:1.socket:2 hwloc-bind --get

On one of the hwloc developer's machines, this example reports "0x00004444,0x44000000". The mask reported on your machine may be different.

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.socket:2` echo hello

Memory binding may also be reported:

hwloc-bind --membind node:1 --mempolicy interleave -- hwloc-bind --get --membind

This returns a string describing the memory binding, such as "0x000000f0 (interleave)". Note that if the system does not contain any NUMA nodes, the reported string will indicate that the process is bound to the entire system memory (e.g., "0xf...f").

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 retrieve process bindings, or lack of a command to execute.

SEE ALSO¶

hwloc(7), lstopo(1), hwloc-calc(1), hwloc-distrib(1)