Your company here, and a link to your site. Click to find out more.

hwloc-ps - Man Page

List currently-running processes or threads that are bound


hwloc-ps [options]



List all processes, even those that are not bound to any specific part of the machine.

--pid <pid>

Only show process of PID <pid>, even if it is not bound to any specific part of the machine.

--children-of-pid <pid>

Only show process of PID <pid> and its hierarchy of children, even if they are not bound to any specific part of the machine.

--name <name>

Only show processes whose name contains <name>, even if they are not bound to any specific part of the machine. This is not supported on all operating systems.

--uid <uid>

Only show processes of the user whose UID is <uid>, or processes of all users if all is given. By default, only processes of the current user are displayed. This is currently only supported on Linux.

-p --physical

Report OS/physical indexes instead of logical indexes

-l --logical

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

-c --cpuset

Show process bindings as cpusets instead of objects.

-t --threads

Show threads inside processes. If -a is given as well, list all threads within each process. Otherwise, show all threads inside each process where at least one thread is bound. This is currently only supported on Linux.


When the object is bound to different objects, report their common ancestor (even if it may be larger than the actual binding).

-e --get-last-cpu-location

Report  the last processors where the process/thread ran. Note that the result may already be outdated when reported since the operating system may move the tasks to other processors at any time according to the binding.


Include objects disallowed by administrative limitations.

--pid-cmd <cmd>

Append the output of the given command to each PID line. For each displayed process ID, execute the command <cmd> <pid> and append the first line of its output to the regular hwloc-ps line.

--pid-cmd env=<name>

On Linux, try to read the value of environment variable name in each process and display it at the end of the line.

--pid-cmd mpirank

On Linux, try to find the process MPI rank (by querying some widespread environment variables) and display it at the end of the line.

--lstopo-misc <file>

Output a file that may be given to lstopo --misc-from for displaying processes/threads as Misc objects. See Examples below.


Run the tool as a JSON server that waits for other process' requests on a port and sends back binding information. See contrib/hwloc-ps.www/ for details.

--json-port <port>

Use the given port number instead of the default 8888.

-v --verbose

Increase verbosity of the JSON server.


Show only the process short name instead of the path.


Report version and exit.

-h --help

Display help message and exit.


By default, hwloc-ps lists only those currently-running processes that are bound. If -t is given, processes that are not bound but contain at least one bound thread are also displayed, as well as all their threads.

hwloc-ps displays process identifier, command-line and binding.  The binding may be reported as objects or cpusets.

By default, process bindings are restricted to the currently available topology. If some processes are bound to processors that are not available to the current process, they are ignored unless --disallowed is given.

The output is a plain list. If you wish to annotate the hierarchical topology with processes so as to see how they are actual distributed on the machine, you might want to use lstopo --ps instead (which also only shows processes that are bound).

The -a switch can be used to show all processes, if desired.


If a process is bound, it appears in the default output:

   $ hwloc-ps
   4759 Core:0 myprogram

If a process is bound on two cores of a larger package, the output will show these cores. Option --single-ancestor will rather return the package even if it is actually larger than the binding here (the process is not bound to Core:0 of Package:0):

   $ hwloc-ps
   4863        Core:1 Core:2   myprogram
   $ hwloc-ps --single-ancestor
   4863        Package:0       myprogram

If a process is not bound but 3 of his 4 threads are bound, it only appears in the thread-aware output (or if explicitly selected):

   $ hwloc-ps

   $ hwloc-ps -t


   $ hwloc-ps --pid 4759
   4759 Machine:0 myprogram

The output may be a file that lstopo uses for adding Misc objects (more flexible version of lstopo --top):

   $ hwloc-ps --misc-from foo
   $ cat foo
   name=12444 myprogram

   name=12444 mythread1

   name=12444 mythread2

This may be directly given to lstopo:

   $ hwloc-ps --misc-from - | lstopo --misc-from -

On Linux, hwloc-ps may also display some process specific environment variable at the end of the line. This is for instance useful for identify MPI ranks among processes:

   $ hwloc-ps --pid-cmd env=OMPI_COMM_WORLD_RANK


Some widespread MPI specific environment variables (OMPI_COMM_WORLD_RANK, PMIX_RANK, PMI_RANK and SLURM_PROCID) are actually directly recognized by hwloc-ps when requesting the mpirank command:

   $ hwloc-ps --pid-cmd mpirank


Beside reading environment variables, hwloc-ps may also append the output of a custom program. Again, for reading the Open MPI process rank:

   $ hwloc-ps --pid-cmd myscript


where myscript is a shell script doing:

   cat /proc/$1/environ 2>/dev/null | xargs --null --max-args=1 echo | grep OMPI_COMM_WORLD_RANK

See Also

hwloc(7), lstopo(1), hwloc-calc(1), hwloc-distrib(1), and hwloc-ps.www/README

Referenced By

hwloc(7), hwloc-info(1), lstopo(1).

Dec 04, 2023 2.10.0 hwloc