On Tailoring Thread Schedules in Protocol Design: Experimental Results

A number of factors motivate and favor the implementation of communication protocols in user-space. Such protocols can be used to provide multiway connectionless transport in distributed computing and conferencing applications with multiple media. Because of potential overheads resulting from the presence of an OS kernel in the critical path of a communication, user-space protocols may hold the key to optimal communication performance and functionality. As part of a larger study on the implementation of general multiway transport for multiple media, we report our initial experiences on the the use of threads for user-space protocol design. We focus on threads scheduling and UDP-based protocol actions, with scheduling strategies that enable threads to do both application-level and communicationrelated processing. Based on experiments performed on a Sun SPARC 5 LAN environment, we show how different threads scheduling strategies yield different levels of application-processing efficiency..