Research On The Scheduling Algorithms In Real-Time Multimedia Systems

With the development of computer technology and network technology, real-time multimedia systems such as video surveillance, remote conference, and gradually be applied to all areas of society. Different storage and multimedia system storage utilization mode, real-time multimedia systems in addition to real-time characteristics, in addition to sudden large amount of data. In order to better provide services, real-time multimedia systems, a higher demand on the existing collection, storage, transmission and scheduling technology. Among them, the processor scheduling as a key technology of the system, under the control of the scheduling algorithm, a reasonable distribution of various system resources to handle multimedia tasks, the system real-time requirements, ensure quality of service (QoS). Traditional scheduling algorithms can not support real-time multimedia systems, so research a new processor scheduling algorithm to become a research focus.In previous studies, the handling of real-time multimedia tasks using traditional periodic task model, on the basis of this model on this basis, many of the scheduling algorithm based on this model be extended out classic monotonic ratio algorithm for the RM (Rate Monotonic) and earliest deadline first algorithm (Earliest The Deadline First), these algorithms for hard real-time system support is better, can not meet the real-time multimedia systems. After people and improve the algorithm, pessimistic approach, optimistic approach and prediction methods. However, due to the characteristics of the real-time multimedia sudden, the cycle is not fixed, these algorithms in real-time tasks, scheduling there are some problems in the test conditions and processor utilization, quality of service of the system is not guaranteed.This paper analyzes the characteristics of real-time multimedia tasks, learn from the description of the traditional periodic task model and the probability distribution, using the idea of task classification, real-time multimedia tasks are broken down into two tasks:one is a fixed cycle of the task, and the other is the unexpected task. The two types of tasks with different task scheduling algorithms, the cycle of fixed tasks using the EDF algorithm, and unexpected task-based EDF for dynamic dead line method algorithm based on sporadic task scheduling algorithm. In this way, mitigation instantaneous excessive number of tasks the system set lead to unpredictable behavior, make the task of the dead line loss rate was significantly lower. The experiments show that this method to ensure quality of service for real-time multimedia applications, to achieve higher resource utilization, and to make the algorithm more suitable for real-time multimedia application environment.