hwloc-gather-topology (1)

hwloc-gather-topology [options] <path>

-h --help display help message and exit

hwloc-gather-topology saves all the relevant topology files into an archive (<path>.tar.bz2) and the lstopo output (<path>.output). The utility for example stores the /proc/cpuinfo file and the entire /sys/devices/system/node/ directory tree.

These files can be used later to explore the machine topology offline. Once the tarball has been extracted, it may for instance be given to some hwloc command-line utilities through their --input option. It is also possible to override the default topology that the hwloc library will read by setting the extracted path in the HWLOC_FSROOT environment variable.

Both archive and lstopo output may also be submitted to hwloc developers to debug issues remotely.

hwloc-gather-topology is a Linux specific tool, it is not installed on other operating systems.

NOTE: It is highly recommended that you read the hwloc(7) overview page before reading this man page.

To store topology information to be used later (possibly on a different host) please run:

hwloc-gather-topology /tmp/myhost

It will store all relevant topology files in the /tmp/myhost.tar.bz2 archive and the lstopo output in the /tmp/myhost.output file. These files can be transferred on another host for later/offline analysis and/or as the input to various hwloc utilities.

To use these data with hwloc utilities you have to unpack myhost.tar.bz2 archive first:

tar jxvf /tmp/myhost.tar.bz2

A new directory named myhost now contains all topology files. Then you ask various hwloc utilities to use this topology instead of the one of the real machine by passing --input myhost. To display the topology just run:

lstopo --input ./myhost

It is not necessary that the topology is extracted in the current directory, absolute or relative paths are also supported:

lstopo --input /path/to/remote/host/extracted/topology/

To see how hwloc would distribute 8 parallel jobs on the original host:

hwloc-distrib --input myhost --single 8

To get the corresponding physical indexes in the previous command:

hwloc-calc --input myhost --po --li --proclist $(hwloc-distrib --input myhost --single 8)

Any program may actually override the default topology with a given archived one even if it does not have a --input option. The HWLOC_FSROOT environment variable should be used to do so:

HWLOC_FSROOT=myhost hwloc-calc --po --li --proclist $(hwloc-distrib --single 8)

All these commands will produce the same output as if executed directly on the host on which the topology information was originally gathered by the hwloc-gather-topology script.

Upon successful execution, hwloc-gather-topology will exit with the code 0.

hwloc-gather-topology will return nonzero exit status if any kind of error occurs, such as (but not limited to) failure to create the archive or output file.

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