An Accurate and Efficient Time-Division Parallelization of Cycle Accurate Architectural Simulators

This paper proposes a parallel cycle-accurate microarchitectural simulator which efficiently executes its workload by splitting the simulation process along time-axis into many intervals. This time-division parallelization is similar to the concept of trace-splitting parallelization but is completely different from this conventional technique because our simulator assures that its result is perfectly equivalent to what a sequential simulator produces. The assurance of the perfect accuracy is endued by a simple failure recovery mechanism; if i-th interval is simulated by a node with an approximate initial machine state which causes invalid result, the interval is simulated again by the node responsible to (i - 1)-th interval and thus having the correct state at the beginning of i-th interval. In order to reduce the possibility of the interval failure for efficiency, the fully cycle-accurate simulation for an interval is preceded by a partial and thus fast micro architectural simulation including that for caches, branch predictors and their interaction in speculative execution. Another important technique is to check the validity of an interval simulation by comparing approximate and correct initial states with respect to their effect to the subsequent execution, rather than the raw values of them. The effectiveness of these techniques are exhibited by our SimpleScalar-based implementation and its evaluation with SPEC CPU95 benchmarks which results that 8-node and 16-node parallel simulations achieve up to 5.8-fold and 9.4-fold speedup respectively