Using interpreted CompositeCalls to improve operating system services

A large number of protection domain crossings and context switches is often the cause of bad performance in complex object-oriented systems. We have i dentified the CompositeCall pattern which has been used to address this pro blem for decades. The pattern modifies the traditional client/server intera ction model so that clients are able to build compound requests that are ev aluated in the server domain. We implemented CompositeCalls for both a trad itional OS, Linux, and an experimental object-oriented mu kernel, Off++. In the first case, we learned about implications of applying CompositeCall to a non-object-oriented 'legacy' system. In both experiments, we learned whe n CompositeCalls help improving system performance and when they do not hel p. In addition, our experiments gave us important insights about some perni cious design traditions extensively used in OS construction. Copyright (C) 2000 John Wiley & Sons, Ltd.