Fence placement for legacy Data-Race-Free programs via synchronization read detection

Andrew J McPherson; Vijay Nagarajan; Susmit Sarkar; Marcelo Cintra

doi:10.1145/2835179

Fence placement for legacy Data-Race-Free programs via synchronization read detection

Andrew J McPherson, Vijay Nagarajan, Susmit Sarkar, Marcelo Cintra

School of Computer Science

Research output: Contribution to journal › Article › peer-review

Abstract

Shared-memory programmers traditionally assumed Sequential Consistency (SC), but modern systems have relaxed memory consistency. Here, the trend in languages is towards Data-Race-Free (DRF) models, where, assuming annotated synchronizations and the program being well-synchronized by those synchronizations, the hardware and compiler guarantee SC. However, legacy programs lack annotations, so even well-synchronized (legacy DRF) programs aren’t recognized. For legacy DRF programs, we can significantly prune the set of memory orderings determined by automated fence placement, by automatically identifying synchronization reads. We prove our rules for identifying them conservative, implement them within LLVM, and observe a 30% average performance improvement over previous techniques.

Original language	English
Article number	46
Number of pages	23
Journal	ACM Transactions on Architecture and Code Optimization (TACO)
Volume	12
Issue number	4
DOIs	https://doi.org/10.1145/2835179
Publication status	Published - 7 Jan 2016

Keywords

Fence placement
Relaxed memory models

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10.1145/2835179

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© 2015, Publisher / the Author(s). This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at dl.acm.org / https://dx.doi.org/10.1145/2835179
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Cite this

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abstract = "Shared-memory programmers traditionally assumed Sequential Consistency (SC), but modern systems have relaxed memory consistency. Here, the trend in languages is towards Data-Race-Free (DRF) models, where, assuming annotated synchronizations and the program being well-synchronized by those synchronizations, the hardware and compiler guarantee SC. However, legacy programs lack annotations, so even well-synchronized (legacy DRF) programs aren{\textquoteright}t recognized. For legacy DRF programs, we can significantly prune the set of memory orderings determined by automated fence placement, by automatically identifying synchronization reads. We prove our rules for identifying them conservative, implement them within LLVM, and observe a 30\% average performance improvement over previous techniques. ",

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N2 - Shared-memory programmers traditionally assumed Sequential Consistency (SC), but modern systems have relaxed memory consistency. Here, the trend in languages is towards Data-Race-Free (DRF) models, where, assuming annotated synchronizations and the program being well-synchronized by those synchronizations, the hardware and compiler guarantee SC. However, legacy programs lack annotations, so even well-synchronized (legacy DRF) programs aren’t recognized. For legacy DRF programs, we can significantly prune the set of memory orderings determined by automated fence placement, by automatically identifying synchronization reads. We prove our rules for identifying them conservative, implement them within LLVM, and observe a 30% average performance improvement over previous techniques.

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Fence placement for legacy Data-Race-Free programs via synchronization read detection

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Keywords

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