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Embedded Parallel Systems Based on Dynamic Look-Ahead Reconfiguration in Redundant Systems. Stephen Holmes. Introduction. Laskowski and Tudruj
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Embedded Parallel Systems Based on Dynamic Look-Ahead Reconfiguration in Redundant Systems Stephen Holmes
Introduction • Laskowski and Tudruj • Seeks to improve execution time for a multi-processor configuration with a Dynamic Look-Ahead System for the reconfiguration of inter-processor connections
Look-Ahead Dynamic Connection Reconfiguration • Used to predict the optimal configuration of a system • Changes with the program • Changes instituted with crossbar switches • Changes controlled with a control processor (CP)
Branching Task Graph • Developed for this system • Used to optimize look-ahead systems • Weighted version of a directed acyclic graph
Additional Forms of BTG • The extended Assigned Program Graph (XAPG) gives a specified schedule for a program • The Extended Communication Activation Graph (XCAG)
Program Partitions • The program is first put into a list schedule minimizing the number of communications and execution time • Second the optimum set of switches is found for the execution of each section.
Conditional Branch Scheduling • Detection of Mutually-Exclusive paths to use the same resources, and assigned the same time slot • Uses the most used branches for scheduling
Optimization • The optimal configuration of processor connections is found for each of the sections • The lowest number of switches that can be used to implement all of the different configurations is found
Results • Compared to a modified Earliest task first (ETF) system • Measure • tR: reconfiguration time of a single connection • tV: section activation time overhead • a: average time between connection reconfigurations • R= a/(tR+tV): reconfiguration control efficiency
Results • Most significant speedup for systems with low reconfiguration efficiency • Tested on a Strassen matrix multiplication algorithim
Critique • Pros • Optimizes use of multiple processors • Minimizes the reconfiguration time • Cons • Adaptability • Hardware
References • E. Laskowski, M. Tudruj Embedded Parallel Systems Based on Dynamic Look-Ahead Reconfiguration in Redundant Communication Resources, Proceedings of the 9th EUROMICRO Conference on Digital System Design, 2006, pp. 176-179