Full-system simulation of distributed memory multicomputers

In this paper we discuss environments for the full-system simulation of multicomputers. These environments are composed of a large collection of modules that simulate the compute nodes and the network, plus additional linking elements that perform communication and synchronization. We present our own environment, in which we integrate Simics with INSEE. We reuse as many Simics modules as possible to reduce the effort of hardware modeling, and also to simulate standard machines running unmodified operating systems. This way we avoid the error-prone effort of developing drivers and libraries. The environment we propose in this paper enables us to show some of the difficulties we found when integrating diverse tools, and how we were able to overcome them. Furthermore we show some important details to have into account in order to do a valid full-system simulation of multicomputers, mostly related with synchronization and timing. Thus, a trade-off has to be found between simulation speed and accuracy of results.