Evaluation of the throughput computed with a dataflow model : a case study

Providing real-time guarantees in complex, heterogeneous, and embedded multiprocessor systems is an important issue because they affect the perceived quality. Digital signal processing algorithms are often modeled with dataflow models. A guaranteed minimum throughput can be computed from such dataflow model. In this paper we analyze three causes for the difference between the computed and measured throughput. We measure the throughput with a cycle accurate simulation. For our channel equalizer application the measured throughput is 10.1% higher than the computed minimum throughput

Improved force-directed scheduling in high-throughput digital signal processing

This paper discusses improved force-directed scheduling and its application in the design of high-throughput DSP systems, such as real-time video VLSL circuits. We present a mathematical justification of the technique of force-directed scheduling, introduced by Paulin and Knight (1989), and we show how the algorithm can be used to find cost-effective time assignments and resource allocations, allowing trade-offs between processing units and memories. Furthermore, we present modifications that improve the effectiveness and the efficiency of the algorithm. The significance of the improvements is illustrated by an empirical performance analysis based on a number of problem instance

On the Convergence of Ritz Pairs and Refined Ritz Vectors for Quadratic Eigenvalue Problems

For a given subspace, the Rayleigh-Ritz method projects the large quadratic eigenvalue problem (QEP) onto it and produces a small sized dense QEP. Similar to the Rayleigh-Ritz method for the linear eigenvalue problem, the Rayleigh-Ritz method defines the Ritz values and the Ritz vectors of the QEP with respect to the projection subspace. We analyze the convergence of the method when the angle between the subspace and the desired eigenvector converges to zero. We prove that there is a Ritz value that converges to the desired eigenvalue unconditionally but the Ritz vector converges conditionally and may fail to converge. To remedy the drawback of possible non-convergence of the Ritz vector, we propose a refined Ritz vector that is mathematically different from the Ritz vector and is proved to converge unconditionally. We construct examples to illustrate our theory.Comment: 20 page

Dataflow Analysis for Real-Time Embedded Multiprocessor System Design

Dataflow analysis techniques are key to reduce the number of design iterations and shorten the design time of real-time embedded network based multiprocessor systems that process data streams. With these analysis techniques the worst-case end-to-end temporal behavior of hard real-time applications can be derived from a dataflow model in which computation, communication and arbitration is modeled. For soft real-time applications these static dataflow analysis techniques are combined with simulation of the dataflow model to test statistical assertions about their temporal behavior. The simulation results in combination with properties of the dataflow model are used to derive the sensitivity of design parameters and to estimate parameters like the capacity of data buffers