tailieunhanh - Model-Based Design for Embedded Systems- Part 4

Model-Based Design for Embedded Systems- P4: This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. | 6 Model-Based Design for Embedded Systems In addition in many cases the same simulation environment can be used for both function and performance verifications. However most simulationbased performance estimation methods suffer from insufficient corner-case coverage. This means that they are typically not able to provide worst-case performance guarantees. Moreover accurate simulations are often computationally expensive. In other works 5 6 hybrid performance estimation methods have been presented that combine simulation and analytic techniques. While these approaches considerably shorten the simulation run-times they still cannot guarantee full coverage of corner cases. To determine guaranteed performance limits analytic methods must be adopted. These methods provide hard performance bounds however they are typically not able to model complex interactions and state-dependent behaviors which can result in pessimistic performance bounds. Several models and methods for analytic performance verifications of distributed platforms have been presented so far. These approaches are based on essentially different abstraction concepts. The first idea was to extend well-known results of the classical scheduling theory to distributed systems. This implies the consideration of communication delays which cannot be neglected in a distributed system. Such a combined analysis of processor and bus scheduling is often referred to as holistic scheduling analysis. Rather than a specific performance analysis method holistic scheduling is a collection of techniques for the analysis of distributed platforms each of which is tailored toward a particular combination of an event stream model a resource-sharing policy and communication arbitration see 10 11 15 as examples . Several holistic analysis techniques are aggregated and implemented in the modeling and analysis suite for real-time applications MAST 3 . In 12 a more general approach to extend the concepts of the classical scheduling .