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Wybrane zagadnienia szeregowania zadan wieloprocesorowych dla dedykowanych procesorow THE CHOSEN PROBLEMS OF MULTIPROCESSOR TASK SCHEDULING FOR DEDICATED PROCESSORS


In many modern computer systems multiprocessor solutions are more and more often applied. This concerns especially computer systems that are used in the real-time applications. At present the real-time systems constitute the well-defined class of omputer systems. The real-time systems are getting more and more popular in many fields of industry and communication. The real-time systems are used to control telecommunication devices and systems, defense systems, avionics and modern factories. In fact many modern facilities cannot do without them. For example without the real-time systems there would be no nuclear power plants, space ships, jet aircrafts, modern factories with robots etc. The program realized by the real-time computer system is divided into special tasks performing given finctions. In the case of the real-time systems a very important matter is to guarantee that all the task are to be finished before their deadline points. In the case of the hard real-time systems any exceeding task deadline is absolutely intolerable. Such event if happens may lead to uncontrollable behavior of the system, which can cause a disaster, for example an aircraft carsh, a loss of human life etc. To guarantee that the task deadlines will be always met, the task scheduling theory was developed. The main goal of the task scheduling theory is to demonstrate at the system development phase that under all the possible to foreseen circumstances the task deadlines will always be met. There does not exist one universal task scheduling algorithm for all kinds of task. There are separate algorithms for periodic tasks and tasks that are event-triggered. Also there are different algorithms for tasks that are preemptive and for tasks that are not preemptive. There exist also quite different algorithms for tasks that are dediceted for one processor only and for so-called multiprocessor tasks that require for their execution two or more processor at the time. As was earlier mentioned in the case of the real-time systems the most important factor is whether the tasks meet the predefined time constraints. In order to meet the hard time constraints cery often a multiprocessor system is used in stead of a sequential system with only one processor. The multiprocessor system is expected to deliver much more computational power than a single processor ssystem, however, the usage of a multiprocessor system requires simultaneously to solve a non-easy problem of multiprocessor task scheduling. In the paper a brif introduction to the problems of multiprocessor task scheduling is given. Further the case of scheduling a set of independent multiprocessor tasks for four dedicated processors is examined. Multiprocessor systems with four processors are very popular at the present time. For example the Texas Instruments TMS320C80 is a single-chip multiprocessor system composed of four DSP processors. Earlier Texas Instruments offered a personal computer boards with four TMS320C40 processors. The proposed algorithm of multiprocessor task scheduling was called a Divide Uniprocessor Task (DUT) algorithm, because all the tasks dedicated for a single processor are grouped together and then the whole set is divided into two subsets, one of which has the length as close as possible to the execution time of compatible tasks dedicated for orher three proecessors. In the paper the process of multiprocessor task scheduling is illustrated with examples and the results of computer simulations arte also presented.......

【作者名称】: MIROSLAW GAJER
【作者单位】: Katedra Automatyki, Akademia Gorniczo-Hutnicza al. Mickiewicza 30, 30-059 Krakow
【关 键 词】: task scheduling, multiprocessor systems, multiprocessor tasks, real-time systems
【期刊名称】: International journal of electronics and telecommunications
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 108,691,438
【摘要长度】: 3,521
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