Preheating a Mobile File Cache

Peter Honeyman
Associate Research Scientist
Center for Information Technology Integration
University of Michigan
Ann Arbor

Ad hoc methods

Avoid file and attribute cache misses while disconnected
  • vigorous use in anticipation of mobility
  • LRU replacement
    • Effective, but
  • tend not to use laptop in office
  • road and office use differ
  • overaggressive fetching pollutes the cache
    •

    Working set

    Over time, estimate the "working set" for a mobile user
  • pass CacheItems to agent
  • calculate "importance" of referenced files
  • maintain reference counts
  • calculate smoothed estimate
  • setting threshold gives a knob to turn
  • X, /bin, /usr/ucb
    •

    Application specific

    Email (what else?): MH in /afs
  • fetch all subdirs
  • flush files starting with #
  • flush refiled files
    • Agent constructs a profile, client fetches
    Off-client processing avoids polluting client cache

    Agent

    Consider an agent holding proxy callbacks
  • scale is a problem
  • knows when cache is stale, even if client doesn't
  • can construct profile to freshen client cache
    •