Scheduling multiple divisible loads on a linear processor network

Min, Veeravalli, and Barlas have recently proposed strategies to minimize the overall execution time of one or several divisible loads on a heterogeneous linear network, using one or more installments. We show on a very simple example that their approach does not always produce a solution and that, when it does, the solution is often suboptimal. We also show how to find an optimal schedule for any instance, once the number of installments per load is given. Then, we formally state that any optimal schedule has an infinite number of installments under a linear cost model as the one assumed in the original papers. Therefore, such a cost model cannot be used to design practical multi-installment strategies. Finally, through extensive simulations we confirmed that the best solution is always produced by the linear programming approach, while solutions of the original papers can be far away from the optimal

File System Simulation: Hierarchical Performance Measurement and Modeling

File systems are very important components in a computer system. File system simulation can help to predict the performance of new system designs. It offers the advantages of the flexibility of modeling and the cost and time savings of utilizing simulation instead of full implementation. Being able to predict end-to-end file system performance against a pre-defined workload can help system designers to make decisions that could affect their entire product line, involving several million dollars of investment. This dissertation presents detailed simulation-based performance models of the Linux ext3 file system and the PVFS parallel file system. The models are developed using Colored Petri Nets. A performance study, using the models, shows that the obtained results are close to the expected behavior of the real file system. The model shows that file system parameters have significant impact on the performance of the I/O when compared to the parameters of the disk subsystem

Optimal Scheduling Algorithms for Communication Constrained Parallel Processing

With the advent of digital TV and interactive multimedia over broadband networks, the need for high performance computing for broadcasting is stronger than ever. Processing a digital video sequence requires considerable computing. One of the ways to cope with the demands of video processing in real-time, we believe, is parallel processing