Analysis and approximation of optimal co-scheduling on Chip Multiprocessors

Cache sharing among processors is important for Chip Multiprocessors to reduce inter-thread latency, but also brings cache contention, degrading program performance considerably. Recent studies have shown that job co-scheduling can effectively alleviate the contention, but it remains an open questio...

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Bibliographic Details
Published in:PACT'08 : proceedings of the Seventeenth International Conference on Parallel Architectures and Compilation Techniques : Toronto, Ontario, Canada, October 25-29, 2008 pp. 220 - 229
Main Authors: Jiang, Yunlian, Shen, Xipeng, Jie, Chen, Tripathi, Rahul
Format: Conference Proceeding
Language:English
Published: ACM 25.10.2008
Subjects:
Algorithm design and analysis
Approximation algorithms
cache contention
CMP scheduling
co-scheduling
Computer science
Degradation
Optimal scheduling
Partitioning algorithms
perfect matching
Schedules
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Summary:Cache sharing among processors is important for Chip Multiprocessors to reduce inter-thread latency, but also brings cache contention, degrading program performance considerably. Recent studies have shown that job co-scheduling can effectively alleviate the contention, but it remains an open question how to efficiently find optimal co-schedules. Solving the question is critical for determining the potential of a co-scheduling system. This paper presents a theoretical analysis of the complexity of co-scheduling, proving its NP-completeness. Furthermore, for a special case when there are two sharers per chip, we propose an algorithm that finds the optimal co-schedules in polynomial time. For more complex cases, we design and evaluate a sequence of approximation algorithms, among which, the hierarchical matching algorithm produces near-optimal schedules and shows good scalability. This study facilitates the evaluation of co-scheduling systems, as well as offers some techniques directly usable in proactive job co-scheduling.
DOI:10.1145/1454115.1454146