Accelerating Multiprocessor Simulation with a Memory Timestamp Record

We introduce a fast and accurate technique for initializing the directory and cache state of a multiprocessor system based on a novel software structure called the memory timestamp record (MTR). The MTR is a versatile, compressed snapshot of memory reference patterns which can be rapidly updated during fast-forwarded simulation, or stored as part of a checkpoint. We evaluate MTR using a full-system simulation of a directory-based cache-coherent multiprocessor running a range of multithreaded workloads. Both MTR and a multiprocessor version of functional fast-forwarding (FFW) make similar performance estimates, usually within 15% of our detailed model. In addition to other benefits, we show that MTR has up to a 1.45x speedup over FFW, and a 7.7x speedup over our detailed baseline