Reducing Cross Domain Call Overhead using Batched Futures

Abstract

In many systems such as operating systems and databases it is important to run client code in a separate protection domain so that it cannot interfere with correct operation of the system. Clients communicate with the server by making cross domain calls, but these are expensive, often costing substantially more than running the call itself. This paper describes a new mechanism called batched futures that transparently batches possibly interrelated client calls. Batching makes domain crossings happen less often, thus substantially reducing the cost. We describe how the mechanism is implemented for the Thor object-oriented database system, and presents performance results showing the benefit of the mechanism on various benchmarks.