Modeling Protocol Offload for Message-oriented Communication

In this paper, we present a new, conceptual model that captures the benefits of protocol offload in the context of high performance computing systems. In contrast to the LAWS model, the extensible message-oriented offload model (EMO) emphasizes communication in terms of messages rather than flows. In contrast to the LogP model, EMO emphasizes the performance of the network protocol rather than the parallel algorithm. The extensible message-oriented offload model allows protocol developers to consider the tradeoffs and specifics associated with offloading protocol processing including the reduction in message latency along with benefits associated with reduction in overhead and improvements to throughput. We give an overview of the EMO model and show how our model can be mapped to the LAWS and LogP models. We also show how it can be used to analyze individual messages within TCP flows by contrasting full offload (TCP offload engines) with other approaches, e.g., interrupt coalescing and splintered TCP