A novel deadline driven disk scheduling algorithm for multi-priority multimedia objects

Abstract

In this paper we introduce a new deadline driven disk scheduling algorithm designed for multimedia servers. The proposed algorithm supports real time requests with multiple priorities, e.g., those for di erent object classes in digital library applications. The proposed algorithm enhances utilization of disk bandwidth by a maintaining one queue for all requests, and b optimizing the seek time. Prior schemes, collectively termed Multi-queue schemes", maintain a separate queue for each priority group and optimize the performance of the high priority requests only. When compared with our proposed scheme, our technique provides approximately two order of magnitude improvement in meeting the deadline of low priority requests. In addition, this algorithm provides bo t h a b etter disk utilization and a better average response time. Under certain conditions, our algorithm violates the deadline of a few high priority requests less than 5 out of a million requests.

Scalable multimedia disk scheduling

“…Combining disk utilization with deadline and priority in one disk scheduling algorithm is addressed in [12]. The objective is to propose a disk scheduling algorithm that serves disk requests based on their priority and minimizes the number of deadline misses while maximizing the disk utilization.…”

“…For example, the disk scheduler in [12] deals with real-time disk requests where each request has only one type of priority. To extend the functionality of this algorithm to deal with multiple types of priorities, we use the SF C 1 from the Cascaded-SFC disk scheduler.…”

“…To extend the functionality of this algorithm to deal with multiple types of priorities, we use the SF C 1 from the Cascaded-SFC disk scheduler. The multiple priorities is entered to SF C 1 and the output is considered the absolute priority of the disk request that is entered into the algorithm in [12]. Similarly to extend the BUCKET algorithm [9] to deal with disk utilization, we take the output of the BUCKET algorithm and enter it into SF C 3 of the Cascaded-SFC disk scheduler with the cylinder position of the disk request.…”

“…PanaViss is a video server research prototype [10] for video broadcasting applications. For architecture details of the PanaViss video server, the reader is referred to [12]. The parameters of the disks in PanaViss server are given in Table 1. A milestone in the Cascaded-SFC multimedia disk scheduler is the choice of three space-filling curves for the three stages of Figure 2.…”

“…In attempting to satisfy multiple concurrent and conflicting requirements (e.g., disk bandwidth, deadline, and priority), scheduler designers and algorithm developers depend mainly on heuristics to code the schedulers (e.g., see [1,2,3,5,6,9,12,14,17,20,21]). It is not always clear that these schedulers are equitable to all aspects of the system, or are controllable in a measurable way to favor one aspect of the system over the other.…”