12:45 PM, Thursday, October 25th, 2001
Room 104, Gates Computer Science Building

Aging Through Cascaded Caches: Performance Issues in the Distribution of Web Content

Edith Cohen
AT&T Labs Research

Slides: PPT

About the talk:

The Web is a distributed system, where data is stored and disseminated from both origin servers and caches. Origin servers provide the most up-to-date copy whereas caches store and serve copies that had been cached for a while. Typically, the lifetime-duration of an object is fixed, and as a result, a copy fetched directly from its origin server has maximum time-to-live (TTL) whereas a copy obtained through a cache has a shorter TTL since its age (elapsed time since fetched from the origin) is deducted from its lifetime duration. Thus, a cache that is served from a cache would incur a higher miss-rate than a cache served from origin servers. Similarly, a high-level cache would receive more requests from the same client population than an origin server would have received. As Web caches are often served from other caches (e.g., proxy and reverse-proxy caches), age emerges as an under-studied but important performance factor. We analyse age-related performance issues using different models of cache/source/object relations and different request patterns. We also evaluate the effectiveness of frequent pre-term refreshes by higher- level caches as a means to decrease client misses. This is joint work with Haim Kaplan that was published in SIGCOMM 2001.

About the speaker:

Edith Cohen is a researcher at AT&T Labs-Research. She did her undergraduate and Masters studies at Tel-Aviv University, and received her Ph.D. in Computer Science from Stanford University in 1991. She joined Bell Laboratories in 1991. During 1997, she was in UC Berkeley as a visiting professor. Her research interests include design and analysis of algorithms, combinatorial optimization, Web performance, networking, and data mining.