Networking abstractions and protocols under variable length messages

The size of data shipped over networks of distributed databases has increased substantially with the introduction of multimedia and high performance systems. Therefore, there is a need to understand the behavior and the trade-offs of available data communication abstractions in such settings. In this paper, we consider parameters associated with the abstractions, the impact of their implementation on throughput, and we compare the performance of BSD sockets (TCP, UDP), System V TLI (TCP), and SunOS RPCs (TCP) in the presence of large messages. In such environments, segmentation overhead of UDP messages at the user level outweighs other considerations such as optimal mbuf allocation and full ethernet bandwidth usage. In addition, it is found that the size of buffer areas allocated to TCP sockets gains further importance when sending large messages. We also find that communication induced paging significantly deteriorates the data transmission throughput and suggest a policy to avoid this problem.