Phase-guided Thread-to-core Assignment for Improved Utilization of Performance-Asymmetric Multi-Core Processors

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CPU vendors are starting to explore trade offs between die size, number of cores on a die, and power consump- tion leading to performance asymmetry among cores on a single chip. For efficient utilization of these performance- asymmetric multi-core processors, application threads must be assigned to cores such that the resource needs of a thread closely matches resource availability at the assigned core. This significantly complicates the task of an average pro- grammer. The contribution of this work is a technique for automatically determining the mapping between threads and performance-asymmetric cores of a processor. Our ap- proach, which we call phase-guided thread-to-core assign- ment, builds on a well-known insight that programs exhibit phase behavior. We first take code sections and group them into clusters such that each section in a cluster is likely to exhibit similar runtime characteristics. The key idea is that with this clustering, characteristics of a small number of representative sections in a cluster give insight into the be- havior of the entire cluster. Thus the exhibited characteris- tics of the representative sections on different types of cores can be used for automating thread-to-core assignment at a lower runtime cost. Variations of our technique show up to an average 150% improvement in throughput over the stock Linux scheduler for systems with a constant feed of jobs, while maintaining comparable fairness and efficiency.

Bib Info

  author = {Tyler Sondag and Hridesh Rajan},
  title = {Phase-guided Thread-to-core Assignment for Improved Utilization of Performance-Asymmetric Multi-Core Processors},
  booktitle = {IWMSE '09: Proceedings of the 2nd International Workshop on Multicore Software Engineering},
  location = {Vancouver, Canada},
  month = {May},
  year = {2009},