NAME¶

hwloc-gather-topology - Saves the relevant Linux topology files and the lstopo output for later (possibly offline) usage.

SYNOPSIS¶

hwloc-gather-topology [options] <path>

OPTIONS¶

-h --help display help message and exit

DESCRIPTION¶

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.

EXAMPLES¶

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.

RETURN VALUE¶

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.

SEE ALSO¶

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