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

By: Tyler Sondag and Hridesh Rajan

Abstract

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.

ACM Reference

Sondag, T. and Rajan, H. 2009. Phase-guided Thread-to-core Assignment for Improved Utilization of Performance-Asymmetric Multi-Core Processors. Proceedings of the ICSE Workshop on Multicore Software Engineering, IWMSE, Vancouver, Canada (2009), 73–80.

BibTeX Reference

@inproceedings{SondagRajan2009,
  author = {Tyler Sondag and Hridesh Rajan},
  title = {Phase-guided Thread-to-core Assignment for Improved Utilization of Performance-Asymmetric Multi-Core Processors},
  booktitle = {Proceedings of the ICSE Workshop on Multicore Software Engineering, IWMSE, Vancouver, Canada},
  pages = {73--80},
  year = {2009},
  publisher = {{IEEE} Computer Society},
  doi = {10.1109/IWMSE.2009.5071386},
  abstract = {
  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.},
}