Modeling cache coherence misses on multicores

While maintaining the coherency of private caches, invalidation-based cache coherence protocols introduce cache coherence misses. We address the problem of predicting the number of cache coherence misses in the private cache of a parallel application when running on a multicore system with an invalidation-based cache coherence protocol. We propose three new performance models (uniform, phased and symmetric) for estimating the number of coherence misses from information about inter-core data sharing patterns and the individual core´s data reuse patterns. The inputs to the uniform and phased models are the write frequency and reuse distance distribution of shared data from different cores. This input can be obtained either from profiling the target application on a single core or by analyzing the data access pattern statically, and does not need a detailed simulation of the pattern of interleaving accesses to shared data. The output of the models is an estimated number of coherence misses of the target application. The output can be combined with the number of other kinds of misses to estimate the total number of misses in each core´s private cache. This output can also be used to guide program optimization to improve cache performance. We evaluate our models with a set of benchmarks from the PARSEC benchmark suite on real hardware.