Noncontiguous locking techniques for parallel file systems

  • Authors:

  • Avery Ching;Wei-keng Liao;Alok Choudhary;Robert Ross;Lee Ward

  • Affiliations:

  • Northwestern University, Evanston, Illinois;Northwestern University, Evanston, Illinois;Northwestern University, Evanston, Illinois;Argonne National Laboratory, Argonne, IL;Sandia National Laboratories, Albuquerque, NM

  • Venue:
  • Proceedings of the 2007 ACM/IEEE conference on Supercomputing
  • Year:
  • 2007

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Abstract

Many parallel scientific applications use high-level I/O APIs that offer atomic I/O capabilities. Atomic I/O in current parallel file systems is often slow when multiple processes simultaneously access interleaved, shared files. Current atomic I/O solutions are not optimized for handling noncontiguous access patterns because current locking systems have a fixed file system block-based granularity and do not leverage high-level access pattern information. In this paper we present a hybrid lock protocol that takes advantage of new list and datatype byte-range lock description techniques to enable high performance atomic I/O operations for these challenging access patterns. We implement our scalable distributed lock manager (DLM) in the PVFS parallel file system and show that these techniques improve locking throughput over a naive noncontiguous locking approach by several orders of magnitude in an array of lock-only tests. Additionally, in two scientific I/O benchmarks, we show the benefits of avoiding false sharing with our byte-range granular DLM when compared against a block-based lock system implementation.