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Numerical computation of spectral elements in maxplus algebra
, 1998
"... We describe the specialization to maxplus algebra of Howard’s policy improvement scheme, which yields an algorithm to compute the solutions of spectral problems in the maxplus semiring. Experimentally, the algorithm shows a remarkable (almost linear) average execution time. ..."
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Cited by 50 (4 self)
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We describe the specialization to maxplus algebra of Howard’s policy improvement scheme, which yields an algorithm to compute the solutions of spectral problems in the maxplus semiring. Experimentally, the algorithm shows a remarkable (almost linear) average execution time.
Throughput analysis of synchronous data flow graphs
 In ACSD’06, Proc. (2006), IEEE
, 2006
"... Synchronous Data Flow Graphs (SDFGs) are a useful tool for modeling and analyzing embedded data flow applications, both in a single processor and a multiprocessing context or for application mapping on platforms. Throughput analysis of these SDFGs is an important step for verifying throughput requir ..."
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Cited by 40 (16 self)
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Synchronous Data Flow Graphs (SDFGs) are a useful tool for modeling and analyzing embedded data flow applications, both in a single processor and a multiprocessing context or for application mapping on platforms. Throughput analysis of these SDFGs is an important step for verifying throughput requirements of concurrent realtime applications, for instance within designspace exploration activities. Analysis of SDFGs can be hard, since the worstcase complexity of analysis algorithms is often high. This is also true for throughput analysis. In particular, many algorithms involve a conversion to another kind of data flow graph, the size of which can be exponentially larger than the size of the original graph. In this paper, we present a method for throughput analysis of SDFGs, based on explicit statespace exploration and we show that the method, despite its worstcase complexity, works well in practice, while existing methods often fail. We demonstrate this by comparing the method with stateoftheart cycle mean computation algorithms. Moreover, since the statespace exploration method is essentially the same as simulation of the graph, the results of this paper can be easily obtained as a byproduct in existing simulation tools. 1
Staying Alive As Cheaply As Possible
 IN PROC. OF 7TH INTL. WORKSHOP ON HYBRID SYSTEMS: COMPUTATION AND CONTROL (HSCC), VOLUME 2993 OF LECT. NOTES IN COMP. SCI
, 2004
"... This paper is concerned with the derivation of infinite schedules for timed automata that are in some sense optimal. To cover a wide class of optimality criteria we start out by introducing an extension of the (priced) timed automata model that includes both costs and rewards as separate modellin ..."
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Cited by 38 (21 self)
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This paper is concerned with the derivation of infinite schedules for timed automata that are in some sense optimal. To cover a wide class of optimality criteria we start out by introducing an extension of the (priced) timed automata model that includes both costs and rewards as separate modelling features. A precise definition is then given of what constitutes optimal infinite behaviours for this class of models. We subsequently show that the derivation of optimal nonterminating schedules for such doublepriced timed automata is computable. This
Performance Analysis and Optimization of Latency Insensitive Systems
, 2000
"... Latency insensitive design has been recently proposed in literature as a way to design complex digital systems, whose functional behavior is robust with respect to arbitrary variations in interconnect latency. However, this approach does not guarantee the same robustness for the performance of the d ..."
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Cited by 36 (10 self)
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Latency insensitive design has been recently proposed in literature as a way to design complex digital systems, whose functional behavior is robust with respect to arbitrary variations in interconnect latency. However, this approach does not guarantee the same robustness for the performance of the design, which indeed can experience big losses. This paper presents a simple, yet rigorous, method to (1) model the key properties of a latency insensitive system, (2) analyze the impact of interconnect latency on the overall throughput, and (3) optimize the performance of the final implementation.
Location Privacy In Ubiquitous Computing
, 2005
"... The field of ubiquitous computing envisages an era when the average consumer owns hundreds or thousands of mobile and embedded computing devices. These devices will perform actions based on the context of their users, and therefore ubiquitous systems will gather, collate and distribute much more per ..."
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Cited by 32 (0 self)
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The field of ubiquitous computing envisages an era when the average consumer owns hundreds or thousands of mobile and embedded computing devices. These devices will perform actions based on the context of their users, and therefore ubiquitous systems will gather, collate and distribute much more personal information about individuals than computers do today. Much of this personal information will be considered private, and therefore mechanisms which allow users to control the dissemination of these data are vital. Location information is a particularly useful form of context in ubiquitous computing, yet its unconditional distribution can be very invasive.
Bounding Average Time Separations of Events in Stochastic Marked Graphs
 In Proc. International Symposium on Advanced Research in Asynchronous Circuits and Systems
, 1999
"... Stochastic timed marked graphs are graphical models of concurrent systems such as asynchronous circuits, embedded systems, queuing networks, manufacturing systems, and many automatic control systems. Unlike earlier works in which delays must be fixed or exponential, we allow the models to include ar ..."
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Cited by 24 (6 self)
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Stochastic timed marked graphs are graphical models of concurrent systems such as asynchronous circuits, embedded systems, queuing networks, manufacturing systems, and many automatic control systems. Unlike earlier works in which delays must be fixed or exponential, we allow the models to include arbitrary delay distributions as long as they have finite means. For such models, one important problem is to determine the average Time Separations of Events (TSE's). For example, an efficient means of finding TSE's in such models of asynchronous circuits facilitates both performance analysis as well as performancedriven synthesis. Towards this end, we present a novel technique to obtain upper and lower bounds on the average TSE for arbitrary pairs of system events. The bounds are formulated using a finite segment of the infinite unfolding of the marked graph and can be efficiently evaluated either using statistical sampling or, in some special cases, analytical methods. The resulting bounds...
Performance optimization of latency insensitive systems through buffer queue sizing of communication channels
 in Proc. Int. Conf. Computer Aided Design
, 2003
"... This paper proposes for latency insensitive systems a performance optimization technique called channel buffer queue sizing, which is performed after relay station insertion in the physical design stage. It can be shown that proper queue sizing can reduce or even completely avoid the performance los ..."
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Cited by 24 (1 self)
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This paper proposes for latency insensitive systems a performance optimization technique called channel buffer queue sizing, which is performed after relay station insertion in the physical design stage. It can be shown that proper queue sizing can reduce or even completely avoid the performance loss due to imbalanced relay stations insertion in reconvergent paths. Moreover, the problem of queue sizing and placement of the additional buffers for maximum performance is formulated and studied to properly allocate available chip areas in the layout to communication channels. An algorithm based on mixed integer linear programming is proposed. Experimental results show that queue sizing is effective in improving the performance of latency insensitive systems even under tight area constraints. Moreover, the proposed algorithm is sufficiently efficient in obtaining the optimal solution for systems of practical sizes. 1.
Intermediate Representations for Design Automation of Multiprocessor DSP Systems
 In Design Automation for Embedded Systems
, 2002
"... Abstract. Selftimed scheduling is an attractive implementation style for multiprocessor DSP systems due to its ability to exploit predictability in application behavior, its avoidance of overconstrained synchronization, and its simplified clocking requirements. However, analysis and optimization o ..."
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Cited by 21 (1 self)
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Abstract. Selftimed scheduling is an attractive implementation style for multiprocessor DSP systems due to its ability to exploit predictability in application behavior, its avoidance of overconstrained synchronization, and its simplified clocking requirements. However, analysis and optimization of selftimed systems under realtime constraints is challenging due to the complex, irregular dynamics of selftimed operation. In this paper, we review a number of highlevel intermediate representations for compiling dataflow programs onto selftimed DSP platforms, including representations for modeling the placement of interprocessor communication (IPC) operations; separating synchronization from data transfer during IPC; modeling and optimizing linear orderings of communication operations; performing accurate design space exploration under communication resource contention; and exploring alternative processor assignments during the synthesis process. We review the structure of these representations, and discuss efficient techniques that operate on them to streamline scheduling, communication synthesis, and power management of multiprocessor DSP implementations.
Complexity results for InfiniteHorizon Markov Decision Processes
, 2000
"... Markov decision processes (MDPs) are models of dynamic decision making under uncertainty. These models arise in diverse applications and have been developed extensively in fields such as operations research, control engineering, and the decision sciences in general. Recent research, especially in a ..."
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Cited by 17 (3 self)
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Markov decision processes (MDPs) are models of dynamic decision making under uncertainty. These models arise in diverse applications and have been developed extensively in fields such as operations research, control engineering, and the decision sciences in general. Recent research, especially in artificial intelligence, has highlighted the significance of studying the computational properties of MDP problems. We address
An Experimental Study of Minimum Mean Cycle Algorithms
, 1998
"... We present a comprehensive experimental study of ten leading algorithms for the minimum mean cycle problem. For most of these algorithms, there has not been a clear understanding of their performance in practice although theoretical bounds have been proved for their running times. Only an experiment ..."
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Cited by 17 (1 self)
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We present a comprehensive experimental study of ten leading algorithms for the minimum mean cycle problem. For most of these algorithms, there has not been a clear understanding of their performance in practice although theoretical bounds have been proved for their running times. Only an experimental study can shed light on whether changes in an algorithm that make its running time theoretically more efficient are worth the overhead in terms of their payoff in practice. To this end, our experimental study provides a great deal of insight. In our evaluation, we programmed these algorithms uniformly and efficiently. We systematically compared them on a test suite composed of random graphs as well as benchmark circuits. Above all, our experimental results provide important insights into the individual performance as well as relative performance of these algorithms in practice. One of the most surprising results of this study is that Howard's algorithm, a well known algorithm to the stoch...