XTW, a parallel and distributed logic simulator

Abstract — In this paper, a new event scheduling mechanism XEQ and a new rollback procedure rb-messages are proposed for use in optimistic logic simulation. We incorporate both of these techniques in a simulator XTW. XTW groups LPs into clusters, and makes use of a multi-level queue,XEQ, to schedule events in the cluster. XEQ has an O(1) event scheduling time complexity. Our new rollback mechanism replaces the use of anti-messages by an rb-message, and eliminates the need for an output queue at each LP. Experimental comparisons to Time Warp reveal a superior performance on the part of XTW, while experimental results over large circuits (5-million-gate to 25million-gate) shows XTW scales well with both the size of circuits and the number of processors.

XTW, a parallel and distributed logic simulator

In this thesis, a new parallel synchronization mechanism, XTW, is proposed. XTW is designed for the parallel simulation of large logic circuits on a cluster of computer workstations. In XTW, a new event queue structure, XEQ, is created in order to reduce the cost of event-scheduling; a new message "un-sending" mechanism, "rb-messages", is proposed to reduce the cost of un-sending" previously sent messages. Both theoretical analysis and actual simulations provide evidence that XTW speeds up parallel logic simulations and provides excellent scalability versus the number of processors and the circuit size. An object-oriented parallel logic simulation software framework, XTWFM, is built upon the base of the XTW mechanism. A milliongates circuit, which can not be simulated by our sequential simulator, is successfully simulated by XTWFM over a cluster of 6 "small" PCs. This success demonstrates that a cluster of PCs is an attractive low-cost alternative for large scale circuit simulation