Analytical Modeling the Multi-Core Shared Cache Behavior With Considerations of Data-Sharing and Coherence

Abstract

To mitigate the ever worsening “Power wall” and “Memory wall” problems, multi-core architectures with multi-level cache hierarchies have been widely accepted in modern processors. However, the complexity of the architectures makes modeling of shared caches extremely complex. In this article, we propose a data-sharing aware analytical model for estimating the miss rates of the downstream shared cache under multi-core scenarios. To avoid time-consuming full simulations of the cache architecture required by conventional approaches, the proposed model can also be integrated with our refined upstream cache analytical model, which also evaluates coherence misses with similar accuracies of state-of-the-art approach with only one tenth time overhead. We validate our analytical model against gem5 simulation results under 13 applications from PARSEC 2.1 benchmark suites. Compared to the results from gem5 simulations under 8 hardware configurations including dual-core and quad-core architectures, the average absolute error of the predicted shared L2 cache miss rates is less than 2% for all configurations. After integrated with the refined upstream model with coherence misses, the overall average absolute error in 4 hardware configurations is degraded to 4.82% due to the error accumulations. As an application case of the integrated model, we also evaluate the miss rates of 57 different multi-core and multi-level cache configurations.

Keywords

• Analytical model
• multi-core
• multi-level cache
• data sharing
• coherence