BXI: designing a network for eXascale

BXI, Bull eXascale Interconnect, is the new interconnection network developed by Bull, now an Atos company for High Performance Computing. First an overview of the BXI network is presented. It is designed and optimized for HPC workloads at very large scale. The BXI network is based on the Portals 4 protocol and permits a complete offload of communication primitives in hardware, thus enabling independent progress of computation and communication. We then describe the two BXI ASIC components, the network interface and the switch, and the BXI software environment. The fabric management integrates features for monitoring, performance analysis, quick traffic re-routing and jobs isolation for performance and security. We finally explain how the Bull eXascale platform integrates BXI to build a large scale parallel system and we present some results obtained on the first BXI systems.