Prevent Deadlock and Remove Blocking for Self-Timed Systems

In the design of distributed embedded systems, designers face two problems: how to prevent deadlock and how to improve performance. An accurate model providing abstractions for functionality and performance is important to solve these problems. Self-timed system model that conducts communications based on handshaking protocols is suitable to model these distributed embedded systems. This paper studies the fundamental properties of self-timed systems and proposes solutions of the above two problems. First, we present the necessary and sufficient conditions for a self-timed system constructed from an application to incur deadlocks; then we propose approaches to prevent any deadlocks in constructing self-timed systems. Second, we observe that the different pace of data progressing on two paths, having common source/destination nodes, may cause blocking events (not deadlock) which dramatically degrade the system performance. We establish theorems to detect blocking events and design Mixed-Integer Linear Programming (MILP) formulas to eliminate these events. Experimental results show that most self-timed systems constructed by a straightforward approach incur possible deadlocks, while our proposed methods guarantee no deadlocks. Furthermore, our proposed techniques to eliminate blocking events achieve 48.23 % performance improvements on average, compared with the straightforward approach.