The Experts below are selected from a list of 1782 Experts worldwide ranked by ideXlab platform
Krishan Kumar Saluja - One of the best experts on this subject based on the ideXlab platform.
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VLSI Design - Thermal Extension of the Total Bandwidth Server
2015 28th International Conference on VLSI Design, 2020Co-Authors: Rehan Ahmed, Ayoosh Bansal, Bhuvana Kakunoori, Parameswaran Ramanathan, Krishan Kumar SalujaAbstract:A typical real-time application is composed of periodic tasks with Hard Deadline constraints. It must also service a periodic tasks that are generated in response to external and internal events. In addition to application's timing constraints, it is important that the system never violates thermal constraint due to its increasingly adverse impact on the processing platform. In this work, we propose a scheme for servicing a periodic tasks in thermally constrained Hard real-time systems. We propose an algorithm, T2BS, which is a thermal extension of the Total Bandwidth Server [1]. We show that our algorithm is optimal in the sense that it meets periodic task timing constraints as well as system thermal constraints, and it supports the maximum rate of a periodic arrivals. Through extensive simulations we demonstrate the validity of theoretical results and perform the response time analysis of a periodic tasks.
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thermal extension of the total bandwidth server
International Conference on VLSI Design, 2015Co-Authors: Rehan Ahmed, Ayoosh Bansal, Bhuvana Kakunoori, Parameswaran Ramanathan, Krishan Kumar SalujaAbstract:A typical real-time application is composed of periodic tasks with Hard Deadline constraints. It must also service a periodic tasks that are generated in response to external and internal events. In addition to application's timing constraints, it is important that the system never violates thermal constraint due to its increasingly adverse impact on the processing platform. In this work, we propose a scheme for servicing a periodic tasks in thermally constrained Hard real-time systems. We propose an algorithm, T2BS, which is a thermal extension of the Total Bandwidth Server [1]. We show that our algorithm is optimal in the sense that it meets periodic task timing constraints as well as system thermal constraints, and it supports the maximum rate of a periodic arrivals. Through extensive simulations we demonstrate the validity of theoretical results and perform the response time analysis of a periodic tasks.
Michele Cirinei - One of the best experts on this subject based on the ideXlab platform.
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brute force determination of multiprocessor schedulability for sets of sporadic Hard Deadline tasks
International Conference on Principles of Distributed Systems, 2007Co-Authors: T P Baker, Michele CirineiAbstract:This report describes a necessary and sufficient test for the schedulability of a set of sporadic Hard-Deadline tasks on a multiprocessor platform, using any of a variety of scheduling policies including global fixed task-priority and earliest-Deadline-first (EDF). The contribution is to establish an upper bound on the computational complexity of this problem, for which no algorithm has yet been described. The compute time and storage complexity of the algorithm, which performs an exhaustive search of a very large state space, make it practical only for tasks sets with very small integer periods. However, as a research tool, it can provide a clearer picture than has been previously available of the real success rates of global preemptive priority scheduling policies and low-complexity sufficient tests of schedulability.
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OPODIS - Brute-force determination of multiprocessor schedulability for sets of sporadic Hard-Deadline tasks
Lecture Notes in Computer Science, 2007Co-Authors: Theodore P. Baker, Michele CirineiAbstract:This report describes a necessary and sufficient test for the schedulability of a set of sporadic Hard-Deadline tasks on a multiprocessor platform, using any of a variety of scheduling policies including global fixed task-priority and earliest-Deadline-first (EDF). The contribution is to establish an upper bound on the computational complexity of this problem, for which no algorithm has yet been described. The compute time and storage complexity of the algorithm, which performs an exhaustive search of a very large state space, make it practical only for tasks sets with very small integer periods. However, as a research tool, it can provide a clearer picture than has been previously available of the real success rates of global preemptive priority scheduling policies and low-complexity sufficient tests of schedulability.
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RTSS - A Necessary and Sometimes Sufficient Condition for the Feasibility of Sets of Sporadic Hard-Deadline Tasks
2006 27th IEEE International Real-Time Systems Symposium (RTSS'06), 2006Co-Authors: Theodore P. Baker, Michele CirineiAbstract:This report describes a necessary condition for feasibility of scheduling a set of sporadic Hard-Deadline tasks on identical multiprocessor platforms, which is also a sufficient condition if there is only a single processor. The key contribution is the characterization of the maximum, over all time intervals of a given length, of the amount of computation that must be completed to meet all Deadlines, and a method of computing this function efficiently to any desired degree of accuracy. Empirical data are provided to verify that the new infeasibility test can be computed efficiently and is an improvement over previously known checks for infeasibility.
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A Necessary and Sometimes Sufficient Condition for the Feasibility of Sets of Sporadic Hard-Deadline Tasks
2006 27th IEEE International Real-Time Systems Symposium (RTSS'06), 2006Co-Authors: Theodore P. Baker, Michele CirineiAbstract:This paper describes a necessary condition for feasibility of scheduling a set of sporadic Hard-Deadline tasks on identical multiprocessor platforms, which is also a sufficient condition if there is only a single processor. The key contribution is the characterization of the maximum, over all time intervals of a given length, of the amount of computation that must be completed to meet all Deadlines, and a method of computing this function efficiently to any desired degree of accuracy. Empirical data are provided to verify that the new infeasibility test can be computed efficiently and is an improvement over previously known checks for infeasibility
Dorothy E. Setliff - One of the best experts on this subject based on the ideXlab platform.
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RTSS - Towards an automatic synthesis system for real-time software
[1991] Proceedings Twelfth Real-Time Systems Symposium, 1991Co-Authors: T. E. Smith, Dorothy E. SetliffAbstract:An automatic synthesis system for real-time software is described. It is argued that the presence of strict operation requirements, such as task-level timing constraints and compiler and target platform constraints, guides synthesis. An automatic software synthesis system, RT-SYN, integrates platform characteristics to synthesize real-time software which meets Hard Deadline design requirements. The RT-SYN system has four key features. First, a visual graphical user interface captures application algorithms without implementation specifications. Second, RT-SYN analyzes the task-level data and control flows to produce worst-case timing and space predictions. Third, RT-SYN uses these predictions to choose abstract representations of data structure and algorithm implementations to meet required timing and space constraints. Fourth, RT-SYN synthesizes C code from the selected implementations. Experimental results are given to illustrate these four features. >
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Towards an automatic synthesis system for real-time software
[1991] Proceedings Twelfth Real-Time Systems Symposium, 1991Co-Authors: T. E. Smith, Dorothy E. SetliffAbstract:An automatic synthesis system for real-time software is described. It is argued that the presence of strict operation requirements, such as task-level timing constraints and compiler and target platform constraints, guides synthesis. An automatic software synthesis system, RT-SYN, integrates platform characteristics to synthesize real-time software which meets Hard Deadline design requirements. The RT-SYN system has four key features. First, a visual graphical user interface captures application algorithms without implementation specifications. Second, RT-SYN analyzes the task-level data and control flows to produce worst-case timing and space predictions. Third, RT-SYN uses these predictions to choose abstract representations of data structure and algorithm implementations to meet required timing and space constraints. Fourth, RT-SYN synthesizes C code from the selected implementations. Experimental results are given to illustrate these four features.
Kang G. Shin - One of the best experts on this subject based on the ideXlab platform.
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Derivation and Use of Deadline Information in Real-Time Control Systems
The Springer International Series in Engineering and Computer Science, 1994Co-Authors: Kang G. ShinAbstract:This section presents a method for deriving the Hard Deadline of a real-time control system, which captures the interplay between a controlled process and its controller computer by formally specifying the need of the controlled process in a form understandable to the controller computer. Several examples of deriving and applying the Hard-Deadline information are also presented to demonstrate the importance of the Deadline information.
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Derivation of Hard Deadlines for Real-Time Control Systems
1992 American Control Conference, 1992Co-Authors: Kang G. ShinAbstract:The computation-time delay in the feedback controller of a real-time control system may cause failure to update the control input during one or more sampling periods. A dynamic failure is said to occur if this delay exceeds a certain limit called a Hard Deadline. We present a method for calculating the Hard Deadlines in linear time-invariant control systems. To derive necessary conditions for (asymptotic) system stability, the state difference equation is modified based on an assumed maximum delay and the probability distribution of delays whose magnitudes are less than, or equal to, the assumed maximum delay. Moreover, the allowed state-space - which is derived from given input and state constraints - is used to calculate the Hard Deadline as a function of time and the system state. We also consider a one-shot delay model in which a single event causes a dynamic failure.
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Derivation and application of Hard Deadlines for real-time control systems
IEEE Transactions on Systems Man and Cybernetics, 1992Co-Authors: Kang G. ShinAbstract:A method for calculating the Hard Deadlines in linear time-invariant control systems by considering system stability and the allowed state-space is presented. To derive necessary conditions for asymptotic system stability, the state difference equation is modified based on an assumed maximum delay and the probability distribution of delays whose magnitudes are less than, or equal to, the assumed maximum delay. The allowed state-space-which is derived from given input and state constraints-is used to calculate the Hard Deadline as a function of time and the system state. A one-shot delay model in which a single event causes a dynamic failure is considered. The knowledge of Hard Deadline is applied to the design of error recovery in a triple modular redundant controller computer.
Ralf R. Müller - One of the best experts on this subject based on the ideXlab platform.
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Individual Packet Deadline Constrained Opportunistic Scheduling for a Multiuser System
2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011Co-Authors: Majid M. Butt, Kimmo Kansanen, Ralf R. MüllerAbstract:In this work an opportunistic scheduling scheme is presented and analyzed for a multiuser system. The objective of the proposed scheme is to minimize the system transmit energy in the presence of a Hard Deadline delay constraint for the individual packets. In the large system limit, the scheme is modeled and analyzed in the scenario when arriving packets have associated Deadlines which vary from packet to packet. We introduce transmission thresholds that depend on channel quality and number of time slots left before a packet reaches its Hard Deadline. These thresholds are optimized such that they reflect the interaction of Deadline delay and channel variation, and result in a minimum system energy. The results demonstrate the saving in energy for a system where the applications have individual packet Deadline delay constraints.
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VTC Spring - Individual Packet Deadline Constrained Opportunistic Scheduling for a Multiuser System
2011 IEEE 73rd Vehicular Technology Conference (VTC Spring), 2011Co-Authors: Majid M. Butt, Kimmo Kansanen, Ralf R. MüllerAbstract:In this work an opportunistic scheduling scheme is presented and analyzed for a multiuser system. The objective of the proposed scheme is to minimize the system transmit energy in the presence of a Hard Deadline delay constraint for the individual packets. In the large system limit, the scheme is modeled and analyzed in the scenario when arriving packets have associated Deadlines which vary from packet to packet. We introduce transmission thresholds that depend on channel quality and number of time slots left before a packet reaches its Hard Deadline. These thresholds are optimized such that they reflect the interaction of Deadline delay and channel variation, and result in a minimum system energy. The results demonstrate the saving in energy for a system where the applications have individual packet Deadline delay constraints.
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Hard Deadline constrained multiuser scheduling for random arrivals
2011 IEEE Wireless Communications and Networking Conference, 2011Co-Authors: Majid M. Butt, Kimmo Kansanen, Ralf R. MüllerAbstract:In this work, an opportunistic scheduling scheme for a large multiuser system is proposed. A group of users with good channels are scheduled simultaneously for data transmission and separated by means of superposition coding. The proposed scheduling scheme is analyzed in the large system limit. Random packet arrivals are modeled as constant arrivals with random content size. Transmission thresholds are optimized in such a way that the system energy is minimized while obeying a strict upper bound on the packet delay. We find that the state space representations of systems with either constant or random arrivals are equivalent. Thus, the thresholds optimized for constant arrivals in earlier work are valid for systems with random arrivals as well. Furthermore, we address the option of intentional packet dropping and the trade-off between packet drop rate and required system energy.
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Hard Deadline constrained multiuser scheduling for random arrivals
Wireless Communications and Networking Conference, 2011Co-Authors: Majid M. Butt, Kimmo Kansanen, Ralf R. MüllerAbstract:In this work, an opportunistic scheduling scheme for a large multiuser system is proposed. A group of users with good channels are scheduled simultaneously for data transmission and separated by means of superposition coding. The proposed scheduling scheme is analyzed in the large system limit. Random packet arrivals are modeled as constant arrivals with random content size. Transmission thresholds are optimized in such a way that the system energy is minimized while obeying a strict upper bound on the packet delay. We find that the state space representations of systems with either constant or random arrivals are equivalent. Thus, the thresholds optimized for constant arrivals in earlier work are valid for systems with random arrivals as well.
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WCNC - Hard Deadline constrained multiuser scheduling for random arrivals
2011 IEEE Wireless Communications and Networking Conference, 2011Co-Authors: Majid M. Butt, Kimmo Kansanen, Ralf R. MüllerAbstract:In this work, an opportunistic scheduling scheme for a large multiuser system is proposed. A group of users with good channels are scheduled simultaneously for data transmission and separated by means of superposition coding. The proposed scheduling scheme is analyzed in the large system limit. Random packet arrivals are modeled as constant arrivals with random content size. Transmission thresholds are optimized in such a way that the system energy is minimized while obeying a strict upper bound on the packet delay. We find that the state space representations of systems with either constant or random arrivals are equivalent. Thus, the thresholds optimized for constant arrivals in earlier work are valid for systems with random arrivals as well.
