An implementation and analysis of the virtual interface architecture
SC '98 Proceedings of the 1998 ACM/IEEE conference on Supercomputing
POWER5 System microarchitecture
IBM Journal of Research and Development - POWER5 and packaging
HOTI '07 Proceedings of the 15th Annual IEEE Symposium on High-Performance Interconnects
Design optimization of a highly parallel InfiniBand host channel adapter
Proceedings of the 4th ACM/IEEE Symposium on Architectures for Networking and Communications Systems
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User-level interfaces (ULIs) find increasing application in high-speed network adapters. The Virtual Interface Architecture as the main ULI representative is adopted not only in its native domain of InfiniBand but increasingly also in virtualized TCP/IP adapters. The advantages over socket implementations are low CPU usage combined with low latency communication. The trend towards heavily virtualized systems however creates a new challenge for user-level network interfaces as they have to cope with the increasing virtualization complexity, making it difficult to improve on current communication latencies. In this paper we propose architectural support in the processor for a new, enhanced doorbell mechanism for ULI devices to improve the send performance through payload data movement onloading. Therefore we reuse existing translation lookaside buffers (TLBs) to translate virtual addresses of send data references already in the processing units. Furthermore the I/O controller is adapted to work on those data references and to fetch and forward the data to the device early on. Our simulations show that this concept is able to reduce the average send start latency for single packet sends by up to 50 % compared with the best current concept.