@TechReport{ it:2017-008, author = {Mahdad Davari and Erik Hagersten and Stefanos Kaxiras}, title = {Scope-Aware Classification: Taking the Hierarchical Private/Shared Data Classification to the Next Level}, institution = {Department of Information Technology, Uppsala University}, department = {Division of Computer Systems}, year = {2017}, number = {2017-008}, month = apr, abstract = {Hierarchical techniques are commonplace in ameliorating the bottlenecks, such as cache coherence, in the design of scalable multi/manycores. Furthermore, there have been proposals to simplify the coherence based on the data-race-free semantics of the software and private/shared data classification, where cores self-invalidate their shared data upon synchronizations. However, naive private/shared data classification in the hierarchies nullifies such optimizations by increasing the amount of data misclassified as shared and therefore being needlessly self-invalidated. We introduce a private/shared data classification approach for hierarchical clusters, where a datum is concurrently classified as private and shared with respect to different classification scopes. Such scope-aware classification eliminates the needless self-invalidation of the valid data at synchronizations, resulting in a coherence scheme that reduces the average network traffic and execution time by 30\% and 5\%, respectively. } }