Memory access buffering in multiprocessors
ISCA '86 Proceedings of the 13th annual international symposium on Computer architecture
Reasoning about parallel architectures
Reasoning about parallel architectures
Checking Cache-Coherence Protocols with TLA+
Formal Methods in System Design
Handbook of automated reasoning
Handbook of automated reasoning
Proceedings of the 32nd ACM SIGPLAN-SIGACT symposium on Principles of programming languages
IWOMP'05/IWOMP'06 Proceedings of the 2005 and 2006 international conference on OpenMP shared memory parallel programming
Incorporation of OpenMP memory consistency into conventional dataflow analysis
IWOMP'08 Proceedings of the 4th international conference on OpenMP in a new era of parallelism
Hi-index | 0.00 |
OpenMP [1] is an important API for shared memory programming, combining shared memory's potential for performance with a simple programming interface. Unfortunately, OpenMP lacks a critical tool for demonstrating whether programs are correct: a formal memory model. Instead, the current official definition of the OpenMP memory model (the OpenMP 2.5 specification [1]) is in terms of informal prose. As a result, it is impossible to verify OpenMP applications formally since the prose does not provide a formal consistency model that precisely describes how reads and writes on different threads interact. This paper focuses on the formal verification of OpenMP programs through a proposed formal memory model that is derived from the existing prose model [1]. Our formalization provides a two-step process to verify whether an observed OpenMP execution is conformant. In addition to this formalization, our contributions include a discussion of ambiguities in the current prose-based memory model description. Although our formal model may not capture the current informal memory model perfectly, in part due to these ambiguities, our model reflects our understanding of the informal model's intent. We conclude with several examples that may indicate areas of the OpenMP memory model that need further refinement however it is specified. Our goal is to motivate the OpenMP community to adopt those refinements eventually, ideally through a formal model, in later OpenMP specifications.