Simulation plays an important role in performance evaluation of parallel systems (hardware and software), algorithms and applications. There are various reasons for using a simulator instead of real machines.
Rapid prototyping of a cache coherency protocol could be facilitated by a simulator that supports shared memory. Such a task could be difficult if the right hardware and software resources are not available. Likewise, implementation of a novel parallel file system can potentially involve hacking low level code that one might not have access to. Simulators are not just limited to systems. One of the motivating factors for this project was to provide an environment in which detailed (fine-grained) timings and analysis can be done without uncontrollable pertabations on real machines.
Initially we intended to simulate both the network and the disk subsystem of the IBM SP-2 [5] to do performance studies of a runtime library. In the end, we settled for the former. The next section describes some of the key details of Proteus. The remaining sections focus on the design and performance of the network module.