About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Publication
MM 1994
Conference paper
Scheduling poiicies for an on-demand video server with batching
Abstract
In an on-demand video server environment, clients make requests for movies to a centralized video server. Due to the stringent response time requirements, continuous delivery of a video stream to the client has to be guaranteed by reserving sufficient resources required to deliver a stream. Hence there is a hard limit on the number of streams that can be simultaneously delivered by a server. The server can satisfy multiple requests for the same movie using a single disk I/O stream by sending the same data pages to multiple clients (using the multicast facility if present in the system). This can be achieved by batching requests for the same movie that arrive within a short duration of time. In this paper, we consider various policies for selecting the movie to be multicast. The choice of a policy depends very much on the customer waiting time tolerance before reneging. We show that an FCFS policy that schedules the movie with the longest outstanding request can perform better than the MQL policy that chooses the movie with the maximum number of outstanding requests. Additionally, if the user behavior can be influenced by guaranteeing maximum waiting time then it may be beneficial to pre-Allocate a fixed number of streams for popular movies. Finally, we demonstrate using empirical distribution for movie requests, that a substantial reduction (of the order of 60%) in required server capacity can be achieved by batching.