Computer Science Department
School of Computer Science, Carnegie Mellon University
My Cache or Yours? Making Storage More Exclusive
Theodore M. Wong, John Wilkes*
Also appears in the Proceedings of the USENIX Annual Techincal Conference, 10-15 June 2002, Monterey, CA.
We explore the benefits of a simple scheme to achieve exclusive caching, in which a data block is cached at either a client or the disk array, but not both. Exclusiveness helps to create the effect of a single, large unified cache. We introduce a DEMOTE operation to transfer data ejected from the client to the array, and explore its effectiveness with simulation studies. We quantify the benefits and overheads of demotions across both synthetic and real-life workloads. The results show that we can obtain useful--sometimes substantial--speedups.
During our investigation, we also developed some new cache-insertion algorithms that show promise for multi-client systems, and report on some of their properties.
*Hewlett-Packard Laboratories, Palo Alto, CA.