Reducing Waiting Costs in User - Level

This paper describes a mechanism for reducing the cost of waiting for messages in architectures that allow user-level communication libraries. We reduce waiting costs in two ways: by reducing the cost of servicing interrupts, and by carefully controlling when the system uses interrupts and when it uses polling. We have implemented our mechanism on the SHRIMP multicomputer and integrated it with our user-level sockets library. Experiments show that a hybrid spin-then-block strategy ooers good performance in a wide variety of situations, and that speeding up the interrupt path signiicantly improves performance.