10.6. iWARP Support

10.6.1. How are iWARP devices supported in Open MPI?

Open MPI’s support for iWARP devices has changed over time.

In the Open MPI v5.0.x series, iWARP devices are supported via the OFI (ofi) MTL via the CM (cm) PML.

Note

Prior versions of Open MPI supported iWARP devies via the openib BTL. Open MPI v5.0.x no longer includes the openib BTL.

Specifically, iWARP support is provides through the rxm provider of the OpenFabrics Interfaces library libfabric. There is software emulation involved in the MPI support of iWARP devices (and therefore at least some level of performance degradation), but the current iWARP vendors have chosen not to provide a higher-performance option.

Important

iWARP support is not well tested or maintained in Open MPI. The Open MPI community would love to have a maintainer who can develop and provide support for iWARP devices over time.