Showing papers on "Fair-share scheduling published in 1976"

An integrated work shift scheduling system

Abstract: An integrated work shift scheduling system is developed and applied in the scheduling of 2600 telephone operators in 43 locations of the General Telephone Company of California. The system involves the forecasting of calls on a half-hourly basis, the conversion to operator requirements, the scheduling of tours by a heuristic algorithm, the assignment of operators to tours, and the operation of the system.

Scheduling a Project Under Multiple Resource Constraints: A Zero-One Programming Approach

Abstract: An implicit enumeration (zero-one programming) algorithm is described for solving the multiple-constrained resource, project scheduling problem. The algorithm developed takes special advantage of the structure of the zero-one formulation, resulting in a significant decrease in the amount of computation time required to solve a given multi-resource problem. A description of the computer program for implementing the procedures developed is provided, as are detailed computation results. Because the multiple-constrained resource, project scheduling problem subsumes the job-shop scheduling and other related sequencing problems, extensions of our approach to the machine sequencing problem (along with limited computation results) are also reported.

Route Constrained Fleet Scheduling

Abstract: This paper attempts to provide some insight into the structure of a large class of fleet scheduling problems. Scheduling under fixed due date constraints is shown to be easily solved using a new formulation of the problem. Scheduling under flexible due date constraints is shown to be inherently complex, and strong evidence is given for asserting that no efficient polynomial bounded algorithm exists for solving this problem exactly. A fast heuristic approach is described which has worked well in some school bus scheduling applications.

Note---A Note on the Single-Machine Multi-Product Lot Scheduling Problem

Abstract: This note develops a procedure for automatically generating feasible solutions for the single-machine multi-product lot scheduling problem.

Technical Note-Finding Some Essential Characteristics of the Feasible Solutions for a Scheduling Problem

Abstract: This note is concerned with some essential characteristics of the feasible solutions for a job-shop scheduling problem in which the jobs are constrained by fixed starting times and due dates. These characteristics are related to the scheduling order of operations on each machine and to the fixed starting and completion times for each operation. We present the basic principles enabling one to define these characteristics and propose a procedure for finding them.

An anomaly in disk scheduling: a comparison of FCFS and SSTF seek scheduling using an empirical model for disk accesses

Abstract: A model for disk accesses based on published measurements is developed. The model is used to show that under highly probable conditions, FCFS seek scheduling is superior to SSTF scheduling in the sense of having a lower mean queue length. A simple example of an arrival sequence illustrating this anomaly is presented.

Finding Some Essential Characteristics of the Feasible Solutions for a Scheduling Problem

Abstract: This note is concerned with some essential characteristics of the feasible solutions for a job-shop scheduling problem in which the jobs are constrained by fixed starting times and due dates. These characteristics are related to the scheduling order of operations on each machine and to the fixed starting and completion times for each operation. We present the basic principles enabling one to define these characteristics and propose a procedure for finding them.

Heuristic Scheduling of Activities under Resource and Precedence Restrictions

Abstract: This paper extends the field of heuristic algorithms for resource constrained scheduling problems in three important areas. First, an algorithm is introduced where the role of the heuristic scheduling urgency factor is expanded from one of solely determining the order in which activities are considered for scheduling at a given instant, to one of determining the combination of activities to be scheduled at this instant. Second, a new hybrid scheduling urgency factor capitalizing on the fact that this algorithm is sensitive to the absolute value rather than relative sequence of the urgency factors is introduced. Finally, a systematic approach to the evaluation of such algorithms is introduced. This includes the identification of relevant problem attributes and the adoption of evaluative concepts such as computational efficiency and analytic and systems effectiveness.

The theory-practice gap in job-shop scheduling

Abstract: This job-shop scheduling problem is perhaps the most common form of industrial scheduling problem, it is also probably the most complex. This paper examines the nature of the problem and reviews the state of the art of scheduling theory and its relevance to the solution of practical problems.

Scheduling Techniques for Operating Systems

Abstract: One of the primary functions of an operating system is to distribute the resources under its control among the users of the system in such a way as to achieve installation standards of performance (including service).

Periodic Job Scheduling in a Distributed Processor System

Abstract: This investigation considers the problem of the nonpreemptive scheduling of a set of independent periodic jobs in a computer system characterized by a collection of processors, memories, and interconnection mechanisms. Such a collection of resources can be used to perform the functions of a process control environment as are found, for example, in the avionics of a military or commercial aircraft. The distribution of these resources permits weight, volume, power, cost, and reliability requirements to be satisfied. Each periodic job is characterized by its frequency and its execution time. The inverse of the frequency, the period, is assumed to be an integer, and the initiation time and the completion time of job must be strictly met. An optimal algorithm is developed for a job set whose members are related by a binary frequency distribution. That is, if the jobs in the set are ordered in terms of decreasing job execution frequency, then fi = 2fi+1. The optimal result is generalized to include conditions in which the jobs are related by fi = kfi+1, where k is an integer.

A decision-making process for the real time control of a production unit†

Abstract: The scheduling of jobs on machines in a job-shop is considered using a multilevel decision-making structure The levels are coordinated by considering as constraints on one level the decision made on the preceding level For job-shop scheduling a tool is proposed to enable one to find and to analyse the set of feasible schedules in the light of the decision taken on the previous level The information obtained as to the earliest starting and latest finishing times for performing the operations, as well as the logical sequence constraints acts as decision aids for the scheduling of the operations The decision is made by choosing, from amongst the actions which are possible in the light of the overall objective, an action which takes into account secondary elements and considerations particular to the job-shop

Stochastic modeling of processor scheduling with application to data base management systems

Abstract: This paper is concerned with the stochastic modeling of processor scheduling and of queuing due to contention for resources in data base management systems. The processing services rendered in searching the data base and retrieving and processing information are modeled explicitly, as is the algorithm used to schedule these services on the processor. The scheduling of the processor is based on a total priority ordering of a set of queues for processing service. A queuing model incorporating the processor scheduling algorithm for IMS (Information Management System) is formulated in order to illustrate the modeling ideas. The model is analyzed under rather general distributional assumptions, based on the observation that certain stochastic processes in the model are cumulative processes defined over the same embedded semi-Markov process. The model is not used in a performance study of IMS, nor is it proposed that the model developed here is one upon which a performance study of IMS should be undertaken. The model should be viewed as illustrative of stochastic models which can be constructed to incorporate algorithms for processor scheduling.

On the Computational Complexity of a Generalized Scheduling Problem

Abstract: The parallel scheduling of a partially ordered set of tasks has received great attention. The partially ordered tasks can be viewed as components of a straight-line program. In this note, we discuss some aspects of the nonpreemptive parallel scheduling of a program with more general control structures. We examine the existence of optimal k-processor schedules, and in line with recent interest in the complexity of computer computations and algorithms, we study the complexity of constructing optimal k-processor schedules. In particular we show that, for every k > 1, any algorithm that would yield an optimal k-processor schedule of a loop-free program, when such a schedule exists, will be of exponential-time complexity.

Critical Ratio Scheduling with Queue Waiting Time Information: An Experimental Analysis

Abstract: The Critical Ratio and Slack Time priority scheduling rules have been applied by a number of firms in computer-based scheduling systems for manufacturing operations. One question in using these rules is whether queue waiting time estimates for individual machines should be used in making scheduling decisions. Simulation experiments are reported in this paper that measure the effect of including historical queue time data in the Critical Ratio and Slack Time rules. The results suggest that such data can adversely affect shop performance, measured using criteria such as job flow times, job lateness, and inventory system costs.

Systematic programming of scheduling algorithms

Abstract: This paper applies the technique of systematic (or structured) programming for programming scheduling algorithms as encountered in operating system design. Monitors are used for structuring scheduling algorithms and a synchronizing method is proposed for process scheduling. Some fairly difficult scheduling problems are solved systematically to illustrate the usefulness of the monitor concepts and the synchronizing method. Certain implementation aspects are also discussed.

Job shop scheduling—A case study

Abstract: A missile range is essentially a large-scale job-shop, involving prodigious amounts of test equipment and formidable problems of coordination. Because of its characteristics, a missile range can be considered a one-machine, N-job situation. For this problem the major scheduling methods were examined and tested, but all were discarded as unfeasible except one which used a Monte Carlo scheduling procedure adjoined with statistical stopping rules. An algorithm based on these ideas was constructed, and it has proven to be flexible and workable, providing predictably near optimum schedules for the missile range within a probabilistic and statistical framework. Even though there is not total implementation yet, considerable benefits to the missile range have already been experienced. For example, in order to automate the scheduling process, it was necessary to codify the goals of the range, something that had never been formalized before. This involved an unprecedented scrutiny and precision of definition of these goals, and from this study a reasonable numerical optimization criterion was constructed. Also, in order to use any automated scheduling algorithm, data files had to be stored on tape for ready access, which in turn has improved other operations on the missile range that were dependent on these data. Furthermore, the scheduling algorithm is providing conflict-free schedules in a few minutes of computer time.

Edp-assisted fleet scheduling in tramp and coastal shipping

Abstract: Advanced benefits in the pool result can be achieved by applying modern scheduling techniques, in conjunction with electronical data processing. Even with a fleet of only five ships, the detailed computer system proved to be superior to manual techniques of experienced schedulers. The computed schedule permitted, on the average, each ship to be assigned to additional jobs for one day per month. This effect increases relative to the number of ships scheduled. For an EDP-system to be effective it is necessary to use the basic information concerning the scheduling; including information on short term alterations, such as subletting or offers on the free market. The analysis of changes within the scheduling system normally involves a great manual effort. To overcome this problem the scheduler is able to communicate on line, in dialogue with the computer through the console, direct from his workplace. Depending upon the required information and the urgency of the reply, the scheduler is able to select, at distinct levels, an analysis of the effect of a particular operation. At the first stage, he obtains the variations of the economic pool result by changes and decisions relative to the schedule. At the next level, notice of the best possibilities of voyage combinations and assignments for ships and contracts are given. In the last stage, the system computes the schedule with the best pool result.

Multi-queue scheduling of two tasks

Abstract: Scheduling in the central server queueing model, consisting of a "CPU" server and m "I/O" servers, is considered for the case of two customers. Optimal (maximal CPU utilization) CPU and I/O schedules are obtained. The best CPU schedule depends on the I/O schedule in effect; and is either Longest or Shortest-Expected-Remaining-Processing-Time-First. However, for certain I/O schedules the CPU schedule is immaterial. The best I/O schedule is always to process the longer CPU customer first.

Multi-queue scheduling of two tasks

Abstract: A class of schedules in the two customer central server queueing model, consisting of a “CPU” server and m “I/O” servers, is considered. Optimal (maximal CPU utilization) CPU and I/O schedules are obtained. The best CPU schedule depends on the I/O schedule in effect; and is either Longest or Shortest-Expected-Remaining-Processing-Time-First. However, for certain I/O schedules the CPU schedule is immaterial. The best I/O schedule is always to process the (expected) longer CPU customer first.

A new approach for the optimum solution of the M by J production scheduling problem

Abstract: The purpose of this paper is to develop an algorithm which solves the M by J scheduling problem on the basis of interatively changing the data of the problem while maintaining an optimum solution along the path. The algorithm is applicable to a rather broad class of optimization problems of the classical O.R. (operations research) literature where objective functions are involved which have a certain monotony property with respect to the data variables of the problem. The algorithm is then applied to the M by J scheduling problem. The approach highlights the required research in the area of analysing the structure of the set of optimum solutions of a problem which could lead to much more efficient solutions to practical problems in manufacturing industry than the available methods of O.R.

A Series-Parallel Multiple-Criteria Model for a Scheduling Problem in the Dress-Making Industry

Abstract: In industrial scheduling problems, before finding suitable algorithms for solving mathematical programs, one often encounters difficulties in formulation and formalizing the problems themselves. This is especially the case when some optimal control is desired. There are several reasons for this: (a) It is difficult to arrive at a general agreement on defining what are precisely good (or optimal) operating conditions of the manufacturing process. (b) There are generally many criteria and constraints inter-related each to the other in a complex manner. (c) Data are not always available.