A characterization of sharing in parallel programs and its application to coherency protocol evaluation

Trace-driven simulation is used to analyze the memory reference patterns of write-shared data in several parallel applications. A characterization of write sharing is developed (based on the notion of a write run), and the traces are examined using metrics derived from the characterization. The results indicate that the amount of write sharing in all programs is small, and that it is characterized by short-to-medium sequences of per-processor references, with little contention for either data or locks. A simple model of write sharing is developed from the write run characterization. By applying the results of the sharing analysis to the model, weighted by machine-specific cycle costs for carrying out coherency-related bus-operations, relative protocol performance can be estimated. These results are compared to those from detailed architectural simulations