Flexible disk scheduling for multimedia presentation servers
Multimedia presentations (e.g., lectures, digital libraries) normally include discrete media objects, such as text and images, along with continuous media objects, such as video and audio. Delivery of the objects composing a multimedia presentation is based on temporal relationships specified by the author(s). Hence, even discrete media objects (that do not normally have any real-time characteristics) have temporal constraints on their presentation. Composition of multimedia presentations may be light (without any accompanying video or large multimedia data) or heavy (accompanied by video for the entire presentation duration). This varying nature of the composition of multimedia presentations provides some flexibility for scheduling their retrieval. Depending on the composition of multimedia presentations, disk access for retrieval may not be needed in every round. For instance, a medium multimedia presentation may need few slots once in, say, every five/six rounds, since the client will take time to consume (view) the presentation. Hence, a presentation can skip a certain number of disk scheduling rounds before retrieving the next required chunk of data. We present a min-max skip round disk scheduling strategy that can admit multimedia presentations in a flexible manner depending on their composition.