Caching with time windows
Conference Paper
We consider the (weighted) Paging with Time Windows problem, which is identical to the classical weighted paging problem but where each page request only needs to be served by a given deadline. This problem arises in many practical applications of online caching, such as the deadline I/O scheduler in the Linux kernel and video-on-demand streaming. From a theoretical perspective, this generalizes the caching problem to allow delayed service, a line of work that has recently gained traction in online algorithms (e.g., Emek et al. STOC '16, Azar et al. STOC '17, Azar and Touitou FOCS '19, etc.). Our main result is an O(log k log n)-competitive algorithm for the Paging with Time Windows problem on n pages with a cache of size k. This significantly improves on the previous best bound of O(k) (Azar et al. (STOC '17). We also consider the offline version of this problem, for which we give an O(1) approximation algorithm and prove APX-hardness. These are the first results for the offline problem; even NP-hardness was not known before our work. At the heart of our algorithms is a novel hitting-set LP relaxation of this problem that overcomes the Omega(k) integrality gap of the natural LP for the problem. To the best of our knowledge, this is the first example of an LP-based algorithm for an online algorithm with delays/deadlines.
Full Text
Duke Authors
Cited Authors
- Gupta, A; Kumar, A; Panigrahi, D
Published Date
- June 8, 2020
Published In
Start / End Page
- 1125 - 1138
International Standard Serial Number (ISSN)
- 0737-8017
International Standard Book Number 13 (ISBN-13)
- 9781450369794
Digital Object Identifier (DOI)
- 10.1145/3357713.3384277
Citation Source
- Scopus