Title:
Adaptive Transaction Scheduling for Transactional Memory Systems
Adaptive Transaction Scheduling for Transactional Memory Systems
Author(s)
Yoo, Richard M.
Lee, Hsien-Hsin Sean
Lee, Hsien-Hsin Sean
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Abstract
Transactional memory systems are expected to enable parallel programming at lower programming
complexity, while delivering improved performance over traditional lock-based systems. Nonetheless, we
observed that there are situations where transactional memory systems could actually perform worse, and
that these situations will actually become dominant in future workloads as more and larger-scale trans-
actional memory systems are available. Transactional memory systems can excel locks only when the
executing workloads contain sufficient parallelism. When the workload lacks the inherent parallelism,
blindly launching excessive transactions can adversely result in performance degradation. To quantita-
tively demonstrate the issues, we introduce the concept of effective transactions in this paper. We show
that the effectiveness of a transaction is closely related to a dynamic quantity we call contention inten-
sity. By limiting the contention intensity below the desired level, we can significantly increase transaction
effectiveness. Increased effectiveness directly increases the overall performance of a transactional memory
system. Based on our study, we implemented a transaction scheduler which not only guarantees that hard-
ware transactional memory systems perform better than locks, but also significantly improves performance
for both the hardware and software transactional memory systems.
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Date Issued
2007
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Text
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Technical Report