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Heterogeneous-race-free memory models

Hower, Derek R.; Hechtman, Blake A.; Beckmann, Bradford M.; Gaster, Benedict R.; Hill, Mark D.; Reinhardt, Steven K.; Wood, David A.


Derek R. Hower

Blake A. Hechtman

Bradford M. Beckmann

Benedict Gaster
Associate Professor in Physical Computing

Mark D. Hill

Steven K. Reinhardt

David A. Wood


Commodity heterogeneous systems (e.g., integrated CPUs and GPUs), now support a unified, shared memory address space for all components. Because the latency of global communication in a heterogeneous system can be prohibitively high, heterogeneous systems (unlike homogeneous CPU systems) provide synchronization mechanisms that only guarantee ordering among a subset of threads, which we call a scope. Unfortunately, the consequences and semantics of these scoped operations are not yet well understood. Without a formal and approachable model to reason about the behavior of these operations, we risk an array of portability and performance issues. In this paper, we embrace scoped synchronization with a new class of memory consistency models that add scoped synchronization to data-race-free models like those of C++ and Java. Called sequential consistency for heterogeneous-race-free (SC for HRF), the new models guarantee SC for programs with "sufficient" synchronization (no data races) of "sufficient" scope. We discuss two such models. The first, HRF-direct, works well for programs with highly regular parallelism. The second, HRF-indirect, builds on HRF-direct by allowing synchronization using different scopes in some cases involving transitive communication. We quantitatively show that HRF-indirect encourages forward-looking programs with irregular parallelism by showing up to a 10% performance increase in a task runtime for GPUs. Copyright © 2014 ACM.

Start Date Mar 1, 2014
Publication Date Mar 14, 2014
Peer Reviewed Peer Reviewed
Pages 427-440
Book Title Proceedings of the 19th international conference on Architectural support for programming languages and operating systems - ASPLOS '14
APA6 Citation Hower, D. R., Hechtman, B. A., Beckmann, B. M., Gaster, B. R., Hill, M. D., Reinhardt, S. K., & Wood, D. A. (2014). Heterogeneous-race-free memory models. In Proceedings of the 19th international conference on Architectural support for programming languages and operating systems - ASPLOS '14, (427-440).
Keywords memory models, programming languages, theory, formal models
Publisher URL
Additional Information Title of Conference or Conference Proceedings : Proceedings of the ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS)

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