Showing papers on "Fair-share scheduling published in 1993"

A compile-time scheduling heuristic for interconnection-constrained heterogeneous processor architectures

Abstract: The authors present a compile-time scheduling heuristic called dynamic level scheduling, which accounts for interprocessor communication overhead when mapping precedence-constrained, communicating tasks onto heterogeneous processor architectures with limited or possibly irregular interconnection structures. This technique uses dynamically-changing priorities to match tasks with processors at each step, and schedules over both spatial and temporal dimensions to eliminate shared resource contention. This method is fast, flexible, widely targetable, and displays promising performance. >

Routing and scheduling in a flexible job shop by tabu search

Abstract: A hierarchical algorithm for the flexible job shop scheduling problem is described, based on the tabu search metaheuristic. Hierarchical strategies have been proposed in the literature for complex scheduling problems, and the tabu search metaheuristic, being able to cope with different memory levels, provides a natural background for the development of a hierarchical algorithm. For the case considered, a two level approach has been devised, based on the decomposition in a routing and a job shop scheduling subproblem, which is obtained by assigning each operation of each job to one among the equivalent machines. Both problems are tackled by tabu search. Coordination issues between the two hierarchical levels are considered. Unlike other hierarchical schemes, which are based on a one-way information flow, the one proposed here is based on a two-way information flow. This characteristic, together with the flexibility of local search strategies like tabu search, allows to adapt the same basic algorithm to different objective functions. Preliminary computational experience is reported.

Scheduling algorithms for multihop radio networks

Abstract: Algorithms for transmission scheduling in multihop broadcast radio networks are presented. Both link scheduling and broadcast scheduling are considered. In each instance, scheduling algorithms are given that improve upon existing algorithms both theoretically and experimentally. It is shown that tree networks can be scheduled optimally and that arbitrary networks can be scheduled so that the schedule is bounded by a length that is proportional to a function of the network thickness times the optimum. Previous algorithms could guarantee only that the schedules were bounded by a length no worse than the maximum node degree times optimum. Since the thickness is typically several orders of magnitude less than the maximum node degree, the algorithms presented represent a considerable theoretical improvement. Experimentally, a realistic model of a radio network is given and the performance of the new algorithms is studied. These results show that, for both types of scheduling, the new algorithms (experimentally) perform consistently better than earlier methods. >

Heuristic scheduling systems

Abstract: (1995). Heuristic Scheduling Systems. Journal of the Operational Research Society: Vol. 46, No. 4, pp. 543-545.

Heuristic scheduling systems : with applications to production systems and project management

Abstract: Partial table of contents: PRELIMINARIES Approaches to Scheduling Book Summary ONE-MACHINE PROBLEMS Single Machine: Foundations Mathematical Solution Methods: New Directions Single Machine: Timing MULTI-MACHINE PROBLEMS Embedded Problems Parallel Machines/Batch Machines Shop Routing FLOW SHOPS AND JOB SHOPS Scheduling Flow Shops: Makespan Scheduling Job Shops: Basic Methods PROJECT SCHEDULING AND MANAGEMENT Network Project Scheduling Resource-Constrained Project Scheduling OTHER ISSUES Model Extensions Planning, Scheduling, and Control Appendices Index

Addressing the gap in scheduling research: a review of optimization and heuristic methods in production scheduling

Abstract: This paper considers the gap between scheduling theory and scheduling practice. The development and the main results of classical scheduling theory are reviewed and presented in an easily accessible way. Recent trends in scheduling research which attempt to make it more relevant and applicable are described. The nature of the gap between theory and practice is discussed. The failure of classical scheduling theory to address the total environment within which the scheduling function operates is noted. However, scheduling research in operations management and manufacturing systems tends to ignore the rich vein of methods, techniques and results in the classical theory. The need for an integrated scheduling research effort, containing elements of both approaches, is stressed.

Method and apparatus for user side scheduling in a multiprocessor operating system program that implements distributive scheduling of processes

Abstract: An integrated software architecture for a highly parallel multiprocessor system having multiple tightly-coupled processors that share a common memory efficiently controls the interface with and execution of programs on such a multiprocessor system. The software architecture combines a symmetrically integrated multithreaded operating system and an integrated parallel user environment. The operating system distributively implements an anarchy-based scheduling model for the scheduling of processes and resources by allowing each processor to access a single image of the operating system stored in the common memory that operates on a common set of operating system shared resources. The user environment provides a common visual representation for a plurality of program development tools that provide compilation, execution and debugging capabilities for multithreaded user programs and assumes parallelism as the standard mode of operation.

HSTS: Integrating Planning and Scheduling

Abstract: : In the traditional approach to managing complex systems, planning and scheduling are two very distinct phases. However, in a wide variety of applications this strict separation is not possible or beneficial. During scheduling it is often necessary to make planning decisions (plan the setup of a machine); moreover planning decisions can benefit from scheduling information (choose a process plan depending on resource loads). HSTS (Heuristic Scheduling Testbed System) is a representation and problem solving framework that provides an integrated view of planning and scheduling. HSTS emphasizes the decomposition of a domain into state variables evolving over continuous time. This allows the description and manipulation of resources far more complex than it is possible in classical scheduling. The inclusion of time and resource capacity into the description of causal justifications allows a fine-grain integration of planning and scheduling and a better adaptation to problem and domain structure. HSTS puts special emphasis on leaving as much temporal flexibility as possible during the planning/scheduling process to generate better plan/schedules with less computation effort. Within the HSTS framework we have implemented several planning/scheduling systems. In the paper we describe an integrated planner and scheduler for short term scheduling of the Hubble Space Telescope. This system has demonstrated the ability to deal effectively with all of the important constraints of the domain. Experimental results show that executable schedules for Hubble can be built in a time compatible with operational needs. The paper also describes a methodology for job-shop scheduling problems. The methodology exploits the temporal flexibility provided by HSTS.

Cyclic transfer algorithms for multivehicle routing and scheduling problems

Abstract: This paper investigates the application of a new class of neighborhood search algorithms—cyclic transfers—to multivehicle routing and scheduling problems. These algorithms exploit the two-faceted decision structure inherent to this problem class: First, assigning demands to vehicles and, second, routing each vehicle through its assigned demand stops. We describe the application of cyclic transfers to vehicle routing and scheduling problems. Then we determine the worst-case performance of these algorithms for several classes of vehicle routing and scheduling problems. Next, we develop computationally efficient methods for finding negative cost cyclic transfers. Finally, we present computational results for three diverse vehicle routing and scheduling problems, which collectively incorporate a variety of constraint and objective function structures. Our results show that cyclic transfer methods are either comparable to or better than the best published heuristic algorithms for several complex and important ...

On-line load balancing with applications to machine scheduling and virtual circuit routing

Abstract: In this paper we study an idealized problem of on-line allocation of routes to virtual circuits where the goal is to minimize the required bandwidth. For the case where virtual circuits continue to exist forever, we describe an algorithm that achieves an O (log n) competitive ratio, where n is the number of nodes in the network. Informally, our results show that instead of knowing all of the future requests, it is sufficient to increase the bandwidth of the communication links by an O(log n) factor. We also show that this result is tight, i.e. for any on-line algorithm there exists a scenario in which O(log n) increase in bandwidth is necessary. We view virtual circuit routing as a generalization of an on-line scheduling problem, and hence a major part of the paper focuses on development of algorithms for non-preemptive on-line scheduling for related and unrelated machines. Specialization of routing to scheduling leads us to concentrate on scheduling in the case where jobs must be assigned immediately upon arrival; assigning a job to a machine increases this machine’s load by an amount that depends both on the job and on the machine. The goal is to minimize the maximum load. For the related machines case, we describe the first algorithm that achieves constant competitive ratio. For the unrekzted case (with n machines), we describe a new method that yields O(log n)-competitive algorithm. This stands in contrast to the natural greedy approach, which we show has only a ~(n) competitive ratio. The virtual circuit routing result follows as a generalization of the unrelated machines case.

Scheduling of manufacturing systems using the Lagrangian relaxation technique

Abstract: The practical solutions for three manufacturing scheduling problems are examined. As each problem is formulated, constraints are added or modified to reflect increasing real world complexity. The first problem considers scheduling single-operation jobs on identical machines. The second problem is concerned with scheduling multiple-operation jobs with simple fork/join precedence constraints on identical machines. The third problem is the job shop problem in which multiple-operation jobs with general precedence constraints are scheduled on multiple machine types Langrangian relaxation is used to decompose each of the scheduling problems into job- or operation-level subproblems. The subproblems are easier to solve than the original problem and have intuitive appeal. This technique results in algorithms which generate near-optimal schedules efficiently, while giving a lower bound on the optimal cost. In resolving the scheduling problem from one time instant to the next, the Lagrange multipliers from the last schedule can be used to initialize the multipliers, further reducing the computation time. >

Engineering and analysis of fixed priority schedulers

Abstract: Scheduling theory holds great promise as a means to a priori validate timing correctness of real-time applications. However, there currently exists a wide gap between scheduling theory and its implementation in operating system kernels running on specific hardware platforms. The implementation of any particular scheduling algorithm introduces overhead and blocking components which must be accounted for in the timing correctness validation process. This paper presents a methodology for incorporating the costs of scheduler implementation within the context of fixed priority scheduling algorithms. Both event-driven and timer-driven scheduling implementations are analyzed. We show that for the timer-driven scheduling implementations the selection of the timer interrupt rate can dramatically affect the schedulability of a task set, and we present a method for determining the optimal timer rate. We analyzed both randomly generated and two well-defined task sets and found that their schedulability can be significantly degraded by the implementation costs. Task sets that have ideal breakdown utilization over 90% may not even be schedulable when the implementation costs are considered. This work provides a first step toward bridging the gap between real-time scheduling theory and implementation realities. This gap must be bridged for any meaningful validation of timing correctness properties of real-time applications. >

Rotation Scheduling: A Loop Pipelining Algorithm

Abstract: We consider the resource-constrained scheduling of loops with inter-iteration dependencies. A loop is modeled as a data flow graph (DFG), where edges are labeled with the number of iterations between dependencies. We design a novel and flexible technique, called rotation scheduling, for scheduling cyclic DFGs using loop pipelining. The rotation technique repeatedly transforms a schedule to a more compact schedule. We provide a theoretical basis for the operations based on retiming. We propose two heuristics to perform rotation scheduling, and give experimental results showing that they have very good performance.

Heuristics for scheduling projects with resource restrictions and several resource-duration modes

Abstract: The problem addressed in this paper is the non-preemptive resource-constrained project scheduling problem in which the duration of each activity depends on the amount of resources allocated to its execution, and the objective is to minimize the overall project duration. It is also assumed that resources are limited but renewable from period to period. Twenty-one heuristic scheduling rules are compared on 240 test problems divided into two main groups containing 50 and 100 activities, respectively. Each group contains one-resource, two-resource and four-resource problems. The results of the comparative study allow us to identify the most efficient heuristics and suggest a combination of five-heuristics which have a high probability (229 over 240) of giving the best (among the 21 solutions obtained) solution.

Scheduling cells in an input-queued switch

Abstract: The authors present two algorithms, IRRM and SLIP-IRRM, for scheduling cells in an input-queued cell switch. Both algorithms exhibit asymptotically 100% use factor under high load, SLIP-IRRM within a single iteration.

Nonpreemptive multi-mode resource-constrained project scheduling

Abstract: This paper addresses methods for formulating and solving a general class of nonpreemptive resource-constrained project scheduling problems in which job durations are discrete functions of committed renewable, nonrenewable and doubly-constrained resources (multi-mode time resource tradeoff). We present a stochastic scheduling method which solves these problems to sub-optimality in an efficient way. Computational results demonstrate that this method is highly superior to other well-known existing deterministic scheduling rules. Extensions to problems in which job-specific (demand) resource profiles are varying with time, in addition to time-varying supply resource profiles, are discussed as well.

The End Of The Line For Static Cyclic Scheduling

Abstract: One common way of constructing hard real-time systems is to use a number of periodic and sporadic tasks assigned static priorities and dispatched at run-time according to the preemptive priority scheduling algorithm. Most analysis for such systems attempts to find the worst-case response time for each task by assuming that the worst-case scheduling point is when all tasks in the system are released simultaneously. Often, however, a given set of hard real-time tasks will have offset constraints: a number of tasks sharing the same periodic behaviour will be constrained to execute at fixed offsets in time relative to each other. In this situation the assumption of a simultaneous release of all tasks can lead to pessimistic scheduling results. In this paper we derive good response time bounds for tasks with offset information, giving an optimal priority ordering algorithm.

Tree structured variable priority arbitration implementing a round-robin scheduling policy

Abstract: An inventive arbiter controls access to a resource in a high speed computer or telecommunications network. The arbiter is capable of performing round-robin scheduling for N requests with P possible priority levels with a sublinear time complexity. The high arbitration speed is achieved through use of a tree structure with a token distribution system for implementing the round-robin scheduling policy.

Static and dynamic scheduling of customer arrivals to a single‐server system

Abstract: In this article we consider a single-server system whose customers arrive by appointments only. Both static and dynamic scheduling problems are studied. In static scheduling problems, one considers scheduling a finite number of customer arrivals, assuming there is no scheduled customer arrival to the system. In dynamic scheduling problems, one considers scheduling one customer arrival only, assuming that there are a number of scheduled customers already. The expected delay time is recursively computed in terms of customer interarrival times for both cases. The objective is to minimize the weighted customer delay time and the server completion time. The problem is formulated as a set of nonlinear equations. Various numerical examples are illustrated. © 1993 John Wiley & Sons, Inc.

Locality and Loop Scheduling on NUMA Multiprocessors

Abstract: An improtant issue in the parallel execution of loops is how to partition and schedule the loops onto the available processors. While most existing dynamic scheduling algorithms manage to load imbalance well, they fail to take locality into account and therefore perform poorly on parallel systems with non-uniform memory access times.

On-line scheduling of hard deadline aperiodic tasks in fixed-priority systems

Abstract: This paper presents a new algorithm for the on-line scheduling of hard deadline aperiodic tasks in a real-time system in which hard deadline periodic tasks are scheduled using a fixed priority algorithm. The algorithm for jointly scheduling the periodic and aperiodic tasks extends the slack stealing algorithm introduced by Lehoczky and Ramos-Thuel (1992), and thus provides the largest amount of time for aperiodic task processing subject to meeting all periodic task deadlines. The analysis permits the periodic tasks to consist of a set of serially executed subtasks each of which has its own fixed execution priority as defined by (Gonzalez Harbour et al., (1991)) Thus the model permits the direct inclusion of operating system functions as well as certain types of synchronization protocols directly into the schedulability analysis. The methods provide a unified framework for dealing with several related problems including: reclaiming unused periodic and aperiodic execution time, load shedding, balancing hard and soft aperiodic execution time and coping with transient overloads. >

A parallel algorithm for broadcast scheduling problems in packet radio networks

Abstract: A parallel algorithm based on an artificial neural network model for broadcast scheduling problems in packet radio networks is presented. The algorithm requires n*m processing elements for an n-mode-m-slot radio network problem. The algorithm is verified by simulating 13 different networks. >

A systematic approach to designing distributed real-time systems

Abstract: The authors describe the use of generalized rate monotonic scheduling (GRMS) theory for the design and analysis of a distributed real-time system. This theory ensures that as long as the system utilization of all tasks lies below a certain bound, and appropriate scheduling algorithms are used, all tasks will meet their deadlines. This puts the development and maintenance of real-time systems on an analytic, engineering basis making, these systems easier to develop and maintain. The authors review the recent extensions of the theory to distributed systems scheduling and examine the architectural requirements for use of the theory. They provide an application example to demonstrate the benefits of this theory. >

Scheduling a flow-line manufacturing cell: a tabu search approach

Abstract: The performance of two heuristic procedures for the scheduling of a flow-line manufacturing cell was compared. We propose a procedure based on a combinatorial search technique known as tabu search. The new procedure is compared with a heuristic based on simulated annealing which was proposed in earlier research. The scheduling problem addressed here differs from the traditional flow-shop scheduling problem in the sense that we are interested in sequencing part families (i.e. groups of jobs which share a similar setup) as well as individual jobs within each family. The results reveal that the tabu search heuristic outperforms the simulated annealing heuristic by generating 'better solutions' in less computation time.

Simultaneous scheduling of machines and automated guided vehicles

Abstract: This paper is an attempt to make scheduling of AGVs an integral part of the overall scheduling activity in an FMS environment. The sequence-dependent nature of travel times for the deadheading trips between successive loaded trips of the AGVs increases the problem difficulty. The problem is decomposed into two subproblems, and previous work on machine scheduling and vehicle scheduling has been exploited to arrive at an iterative heuristic procedure where makespan is the performance criterion. At each iteration, a new machine schedule, generated by a heuristic procedure, is investigated for its feasibility to the vehicle scheduling subproblem. The operation completion times obtained from the machine schedule are used to construct time windows for each material handling trip, and the second subproblem is handled as a sliding time window problem. A set of problems are solved to analyse the impact of the process times/travel times ratio on the performance of the procedure. The interaction between the...