Distributed Process Scheduling - ia State …：分布式进程调度--佐治亚州….ppt

Outline ? Overview ? Process Interaction Models ? A System Performance Model ? Efficiency Loss ? Processor Pool and Workstation Queuing Models ? Comparison of Performance for Workload Sharing ? References For concurrent execution of interacting processes:- ? Communication and ? Synchronization between processes are the two essential ponents Before processes can execute, they need to be:- ? Scheduled and ? Allocated with resources. Why scheduling? enhance overall system performance metrices like: ? pletion time and ? Processor utilization. 2. To achieve location and performance transparencies by distributed process scheduling. Why scheduling in distributed systems is of special interest This is so because of the issues that are different from those in traditional multiprocessor systems: ? The communication overhead is significant. ? The effect of underlying architecture cannot be ignored. ? And the dynamic behaviour of the system must be addressed. Process Models(in brief) 1. Precedence Process Model ? Processes are represented by a DAG. ? Nodes- sequential processes ? Arcs- eg: i to j requires that process pletes before j can start executing. Communication Process Model ? Processes are created to coexist and communicate synchronously. ? So we have undirected edges. Disjoint Process Model ? We assume that processes can be run independently of each other. ? So order in which processes are executed is not important. System Performance ? Speedup ?-What are the factors on which it depends ? How to calculate speedup when we apply these factors Speedup depends on three factors ? The design of the algorithm ? The efficiency of the scheduling algorithm ? The underlying system architecture. ? So if we take ‘S’ as the speedup factor then the above dependencies can be represented as ? S= F(Algorithm, System, Schedule) ? Where ? OSPT= optimal sequential processing time; the best time that can be achieved on a single processor