Next: Introduction

# Predicting File System Actions from Prior Events

Thomas M. Kroeger and Darrell D. E. Long
Department of Computer & Information Sciences
University of California, Santa Cruz

### Abstract:

We have adapted a multi-order context modeling technique used in the data compression method Prediction by Partial Match (PPM) to track sequences of file access events. From this model, we are able to determine file system accesses that have a high probability of occurring as the next event. By prefetching the data for these events, we have transformed an LRU cache into a predictive cache that in our simulations averages 15% more cache hits than LRU. In fact, on average our four-megabyte predictive cache has a higher cache hit rate than a 90 megabyte LRU cache.

- Introduction
- Predictive Caching Method
  - Context Modeling
  - Tracking File System Events
  - Selecting Events to Prefetch
- Simulation
  - Prefetch Threshold
  - Number of Files Prefetched
  - Maximum Order of the Model
  - Improvements Over LRU
  - Cache Size
  - Model Memory Requirements
- Related Work
- Future Work
- Conclusions
- Acknowledgments
- References
- About this document ...