Practical, transparent operating system support for superpages

  • Authors:

  • Juan Navarro;Sitaram Iyer;Peter Druschel;Alan Cox

  • Affiliations:

  • Rice University and Universidad Católica de Chile;Rice University;Rice University;Rice University

  • Venue:
  • OSDI '02 Proceedings of the 5th symposium on Operating systems design and implementationCopyright restrictions prevent ACM from being able to make the PDFs for this conference available for downloading
  • Year:
  • 2002

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Abstract

Most general-purpose processors provide support for memory pages of large sizes, called superpages. Superpages enable each entry in the translation lookaside buffer (TLB) to map a large physical memory region into a virtual address space. This dramatically increases TLB coverage, reduces TLB misses, and promises performance improvements for many applications. However, supporting superpages poses several challenges to the operating system, in terms of superpage allocation and promotion tradeoffs, fragmentation control, etc. We analyze these issues, and propose the design of an effective superpage management system. We implement it in FreeBSD on the Alpha CPU, and evaluate it on real workloads and benchmarks. We obtain substantial performance benefits, often exceeding 30%; these benefits are sustained even under stressful workload scenarios.