This project was supported in part by DARPA contracts/grants N66001-97-C-8522, N66001-97-C-8523, and F19628-95-C-0193, and by Tektronix, Inc. and Intel Corporation.
Proceedings Multimedia Computing and Networking 1998
Multimedia systems - Design, Streaming technology (Telecommunications), Adaptive computing systems
Device independent I/O has been a holy grail to operating system designers since the early days of UNIX. Unfortunately, existing operating systems fall short of this goal for multimedia applications. Techniques such as caching and sequential read-ahead can help mask I/O latency in some cases, but in others they increase latency and add substantial jitter. Multimedia applications, such as video players, are sensitive to vagaries in performance since I/O latency and jitter affect the quality of presentation. Our solution uses adaptive prefetching to reduce both latency and jitter. Applications submit file access plans to the prefetcher, which then generates I/O requests to the operating system and manages the buffer cache to isolate the application from variations in device performance. Our experiments show device independence can be achieved: an MPEG video player sees the same latency when reading from a local disk or an NFS server. Moreover, our approach reduces jitter substantially.
Dan Revel, Dylan McNamee, David Steere, and Jonathan Walpole, "Adaptive Prefetching for Device Independent File I/O," In Proc. SPIE 3310, Multimedia Computing and Networking 1998, 139 (December 29, 1997); doi:10.1117/12.298416