Efficiently adapting to sharing patterns in software DSMs

In this paper we introduce a page-based Lazy Release Consistency protocol called ADSM that constantly and efficiently adapts to the applications´ sharing patterns. Adaptation in ADSM is based on our dynamic categorization of the type of sharing experienced by each page. Pages can be categorized as falsely-shared, migratory, or producer/consumer(s). Migratory and producer/consumer(s) pages are managed in single-writer mode, while falsely-shared data are managed in multiple-writer mode. Coherence is kept with invalidations for most types of the shared data, but updates are used for lock-protected data in migratory state and barrier-protected delta in producer/consumer(s) state. We performed experiments with 6 parallel applications on an 8-node SP2 system, comparing our protocol against standard TreadMarks and a version of TreadMarks that also adapts to sharing patterns. Our results show that ADSM consistently outperforms its competitors; our protocol can improve the TreadMarks speedups by as much as 155%, while surpassing the performance of the adaptive TreadMarks implementation by as much as 67%. Our main conclusions are that our categorization and adaptation strategies are useful techniques for improving the performance of page-based software DSMs, while ADSM is a highly-efficient option for low-cost parallel computing