Scheduling Theory Research Articles

Evolutionary planning of virtualized cyber-physical compute and control clusters

Virtualization technology has the potential to notably advance the automation process in the domain of cyber-physical systems (CPS). It can improve both dependability and availability as well as significantly reduce the procurement, operation and maintenance costs of such systems. However, in the context of virtualization, research has put the most emphasis on topics of hardware utilization and fault-tolerance. There is little literature on how to model, integrate and consolidate a CPS by means of virtualization. In this paper we present a methodology for planning safe and efficient virtualized cyber-physical compute and control clusters execution platforms for time-constrained virtual machines (VMs) that encapsulate CPS applications. We discuss the used methods, describe the corresponding models and the required system architecture. In contrast to typical resource allocation problems from other domains (e.g. cloud computing), in this case, the planning process must take real-time requirements of applications into account. In order to achieve this, we combine evolutionary algorithms with formal system performance analysis in particular algorithms considered in classical scheduling theory. Such an approach allows not only to optimally dimension the compute and control clusters, but also provides strict guarantees regarding the timing predictability of the integrated CPS. Further, the embedment of a formal performance analysis technique notably eases the modeling of a system. As a consequence, the modeling process is fast, flexible and accessible not only to experts but also to system designers as they do not have to struggle with complex and time consuming mathematical formulations. Finally, our approach also provides answers to several practical questions that arise when integrating a CPS by means of virtualization.

Off-site construction optimization: Sequencing multiple job classes with time constraints

Off-site construction is a unique hybrid of manufacturing operations and on-site construction activities. Maximizing the production output has long been the main challenge for off-site manufacturers. Among other responses to this challenge, the use of multi-task shared resources has proved its effectiveness in improving tangible performance measures of production. However, multi-skilled resources often become bottlenecks (overloaded) when producing multiple classes of products and prevent the production network from meeting due dates. This paper analytically models the problem of defining the optimal product sequencing using optimization-based metaheuristics with the aim of minimizing changeover time, which is wasted switching from a product class to another. Production data of two Australian off-site manufacturers are used in the subsequent empirical analysis resulting in advancement of five research propositions. This research contributes to the scheduling theory by expanding the insight into dynamics of resource sharing and job sequencing. The developed models and propositions are of practical value for off-site manufacturers of building elements to maximize their production output.

On the Improved Hard Real-Time Scheduling of Cyclo-Static Dataflow

Recently, it has been shown that the hard real-time scheduling theory can be applied to streaming applications modeled as acyclic Cyclo-Static Dataflow (CSDF) graphs. However, this recent approach is not always efficient in terms of throughput and processor utilization. Therefore, in this article, we propose an improved hard real-time scheduling approach to schedule streaming applications modeled as acyclic CSDF graphs on a Multiprocessor System-on-Chip (MPSoC) platform. The proposed approach converts each actor in a CSDF graph to a set of real-time periodic tasks. The conversion enables application of many hard real-time scheduling algorithms that offer fast calculation of the required number of processors for scheduling the tasks. In addition, we propose a method to reduce the graph latency when the converted tasks are scheduled as real-time periodic tasks. We evaluate the performance and time complexity of our approach in comparison to several existing scheduling approaches. Experiments on a set of real-life streaming applications demonstrate that our approach (1) results in systems with higher throughput and better processor utilization in comparison to the existing hard real-time scheduling approach for CSDF graphs, while requiring comparable time for the system derivation; (2) delivers shorter application latency by applying the proposed method for graph latency reduction while providing better throughput and processor utilization when compared to the existing hard real-time scheduling approach; (3) gives the same throughput as the existing periodic scheduling approach for CSDF graphs, but requires much shorter time to derive the task schedule and tasks’ parameters (periods, start times, and so on); and (4) gives the throughput that is equal to or very close to the maximum achievable throughput of an application obtained via self-timed scheduling, but requires much shorter time to derive the schedule. The total time needed for the proposed conversion approach and the calculation of the minimum number of processors needed to schedule the tasks and the calculation of the size of communication buffers between tasks is in the range of seconds.

A genetic algorithm for permutation flowshop scheduling under practical make-to-order production system

AbstractThe aim of this work is to bridge the gap between the theory and actual practice of production scheduling by studying a problem from a real-life production environment. This paper considers a practical Sanitaryware production system as a number of make-to-order permutation flowshop problems. Due to the wide range of variation in its products, real-time arrival of customer orders, dynamic batch adjustments, and time for machine setup, Sanitaryware production system is complex and also time sensitive. In practice, many such companies run with suboptimal solutions. To tackle this problem, in this paper, a memetic algorithm based real-time approach has been proposed. Numerical experiments based on real data are also been presented in this paper.

A novel key scheduling scheme for AES algorithm

This paper examines the theory of AES key scheduling and its potential problems. We propose a novel key scheduling scheme. The scheme improves the speed of key expansion without increasing computational complexity, reduces the dependency of output key on input key during key expansion, and improves the avalanche effect of key expansion.

Time Management Status of Small Contractors and Suggestions on Education for Time Management in Colleges

A construction manager tries to complete a construction project within its duration and budget using available resources. Schedule networks such as Bar-chart and CPM(critical path method) are used to finish the project within the duration. A survey shows that small contractors prefer Microsoft Excel to commercial time management softwares to manage construction time in their fields, because the Excel is useful to control cost with schedule and few time management experts works in the small contractors. A college produces talented graduates who are able to manage time of a construction project. But the quality and Received (January 12, 2016), Review Result (January 26, 2016) Accepted (February 2, 2016), Published (March 31, 2016) 63243 Dept. architecture, Jeju Nat’l Univ., 102 Jejudaehak-ro, Jeju-si, Jeju-do, Korea email: jangmh@jejunu.ac.kr (Corresponding Author) 63243 Dept. architecture, Jeju Nat’l Univ., 102 Jejudaehak-ro, Jeju-si, Jeju-do, Korea email: ykyi@jejunu.ac.kr * 이 논문은 2000년도 정부(교육과학기술부)의 재원으로 한국연구재단의 기초연구사업 지원을 받아 수행된 것 임(과제번호 2010-0011139). Time Management Status of Small Contractors and Suggestions on Education for Time Management in Colleges Copyright c 2016 HSST 414 quantity of college eduction for time management is insufficient. Another survey shows that majors in Architectural engineering of local national universities have the curriculum for time management, and teach mainly the theory of network scheduling and how to make the network schedule. The several majors have classes for the theory and exercise of commercial time management softwares in several majors. It is necessary to educate time management experts able to use Bar-chart and commercial time management softwares for the small contractors.

The Main and Accessorial Equipment Optimal Schedule for the Steelmaking-Continuous Casting Process

Abstract: The process of steelmaking-continuous casting is the bottleneck of steelmaking production. How to make a cooperative scheduling between the main and accessorial equipment for the steelmaking-continuous casting process is the major factor for the steelmaking production. This paper studies the complex production process scheduling models of the main and accessorial equipment for the steelmaking-continuous casting process and builds the schedule model based on the main and accessorial equipment for the steelmaking-continuous casting process with separable structure. Then, an effective lagrange relaxation iterative algorithm is proposed to improve the optimal efficiency of the static schedule. Finally, the industrial application is verified based on the background of the actual steelmaking and continuous casting schedule in domestic steelmaking plant. The research will improve the schedule method for the actual steelmaking-continuous casting process, promote the development of the schedule theory with the separable structure characteristics and lay a foundation in the industry application for the schedule theory.

Normal-form preemption sequences for an open problem in scheduling theory

Structural properties of optimal preemptive schedules have been studied in a number of recent papers with a primary focus on two structural parameters: the minimum number of preemptions necessary, and a tight lower bound on `shifts', i.e., the sizes of intervals bounded by the times created by preemptions, job starts, or completions. So far only rough bounds for these parameters have been derived for specific problems. This paper sharpens the bounds on these structural parameters for a well-known open problem in the theory of preemptive scheduling: Instances consist of in-trees of $n$ unit-execution-time jobs with release dates, and the objective is to minimize the total completion time on two processors. This is among the current, tantalizing `threshold' problems of scheduling theory: Our literature survey reveals that any significant generalization leads to an NP-hard problem, but that any significant simplification leads to tractable problem. For the above problem, we show that the number of preemptions necessary for optimality need not exceed $2n-1$; that the number must be of order $\Omega(\log n)$ for some instances; and that the minimum shift need not be less than $2^{-2n+1}$. These bounds are obtained by combinatorial analysis of optimal schedules rather than by the analysis of polytope corners for linear-program formulations, an approach to be found in earlier papers. The bounds immediately follow from a fundamental structural property called `normality', by which minimal shifts of a job are exponentially decreasing functions. In particular, the first interval between a preempted job's start and its preemption is a multiple of 1/2, the second such interval is a multiple of 1/4, and in general, the $i$-th preemption occurs at a multiple of $2^{-i}$. We expect the new structural properties to play a prominent role in finally settling a vexing, still-open question of complexity.

Patients scheduling problems with deferred deteriorated functions

In the survey scheduling theory, if a surgical patient is regarded as a job waiting to be processed, and the anesthesiologist care unit nurses as machines that are needed before the survey. Due to the lack of operating rooms or the accidental extension of operation time, the patients will have a longer wait time, and can not do operation following the effects of the anaesthetic. The patient needs to be re-anesthesia so that the effects are required to undergo surgery. But this will cause operation time prolonged. Based on the performance of medical procedures under deteriorating health conditions, this paper presents a deterministic approach to schedule patients in surgery scheduling problems with the deferred parameter. We take the patients as jobs. By the deferred deteriorating effect, it means that the actual processing time of a job is a function of its starting time and a control parameter. We prove that the classical SPT (the shortest processing time) rule remains optimal when we minimize the makespan or the total completion time. For problems of minimizing the total weighted completion time and the maximum lateness, we present heuristic sequencing rules and analyze the worst-case bounds for performance ratios. We also show that these heuristic rules can be optimal under some agreeable conditions between the normal processing times and job due dates or weights.

Resource-provision scheduling in cloud datacenter

Abstract. Cloud computing, the long-held dream of computing as a utility, has the potential to transform a large part of the IT industry, making software even more attractive as a service and shaping the way in which hardware is designed and purchased. We review the new cloud computing technologies, and indicate the main challenges for their development in future, among which resource management problem stands out and attracts our attention. Combining the current scheduling theories, we propose cloud scheduling hierarchy to deal with different requirements of cloud services. we settle the evaluation problem for on-line schedulability tests in cloud computing. We propose a concept of test reliability to express the probability that a random task set could pass a given schedulability test. The larger the probability is, the more reliable the test is. From the aspect of system, a test with high reliability can guarantee high system utilization. From the practical aspect, we develop a simulator to model MapReduce framework. This simulator offers a simulated environment directly used by MapReduce theoretical researchers. The users of SimMapReduce only concentrate on specific research issues without getting concerned about finer implementation details for diverse service models, so that they can accelerate study progress of new cloud technologies.

On Routing and Spectrum Assignment in Rings

We present a theoretical study of the routing and spectrum assignment (RSA) problem in ring networks. We first show that the RSA problem with fixed-alternate routing in general-topology (mesh) networks (and, hence, in rings as well) is a special case of a multiprocessor scheduling problem. We then consider bidirectional ring networks and investigate two problems: 1) the spectrum assignment problem under the assumption that each demand is routed along a single fixed path (e.g., the shortest path), and 2) the general case of the RSA problem whereby a routing decision along the clockwise and counter-clockwise directions must be made jointly with spectrum allocation. Based on insights from multiprocessor scheduling theory, we derive the complexity of the two problems and develop new constant-ratio approximation algorithms with a ratio that is strictly smaller than the best known ratio to date.

Dynamic Scheduling System of Human-Computer Interaction for Steelmaking-Continuous Casting Process Based on Gantt Chart and Optimization Model

With the development of the hardware in Chinese iron industry, scheduling technology is becoming key obstacles that hold back the further development in iron enterprise. And the scheduling theory about the process of steelmaking-continuous casting can’t fit the actual production. To improve this situation, we manage to develop the system the combine the editable Gantt chart and optimization models. On one hand, this system can use Gantt chart to show dispatcher real-time schedule and allow dispatcher reschedule on Gantt chart. On the other hand, the system can detect the change dispatcher made and use the optimization model to complete the whole schedule. In a word, this system takes advantage of the scheduling ability of dispatcher and the high speed calculation of computer to reschedule efficiently.

Unified overhead-aware schedulability analysis for slot-based task-splitting

Hard real- time multiprocessor scheduling has seen, in recent years, the flourishing of semi-partitioned scheduling algorithms. This category of scheduling schemes combines elements of partitioned and global scheduling for the purposes of achieving efficient utilization of the system’s processing resources with strong schedulability guarantees and with low dispatching overheads. The sub-class of slot-based “task-splitting” scheduling algorithms, in particular, offers very good trade-offs between schedulability guarantees (in the form of high utilization bounds) and the number of preemptions/migrations involved. However, so far there did not exist unified scheduling theory for such algorithms; each one was formulated in its own accompanying analysis. This article changes this fragmented landscape by formulating a more unified schedulability theory covering the two state-of-the-art slot-based semi-partitioned algorithms, S-EKG and NPS-F (both fixed job-priority based). This new theory is based on exact schedulability tests, thus also overcoming many sources of pessimism in existing analysis. In turn, since schedulability testing guides the task assignment under the schemes in consideration, we also formulate an improved task assignment procedure. As the other main contribution of this article, and as a response to the fact that many unrealistic assumptions, present in the original theory, tend to undermine the theoretical potential of such scheduling schemes, we identified and modelled into the new analysis all overheads incurred by the algorithms in consideration. The outcome is a new overhead-aware schedulability analysis that permits increased efficiency and reliability. The merits of this new theory are evaluated by an extensive set of experiments.

Optimizing Single-Depot Vehicle Scheduling Problem: Fixed-Interval Model and Algorithm

Intelligent transportation systems (ITS) play an important role in public transit. This study addresses modeling and algorithm for the optimal single-depot vehicle scheduling problem (SDVSP) in the intelligent public transit operation, which has been implemented successfully in practice. The problem is formulated as a fixed-interval scheduling model in accord with job shop scheduling theory, which aims to assign ideal jobs to machines at appropriate times to maximize production in computer science or industrial engineering. This model allows transportation engineers to make use of those out-of-the-box theories and solution methods already developed for fixed-interval scheduling problems. In this article, the SDVSP with multiple vehicle types is established as a non-preemptive online multiprocessor-task fixed-interval scheduling model. As conventional solution methods for solving fixed interval scheduling problems are no longer available for the proposed model, this article develops the algorithm based on the FIFO (first in, first out) rule to find the optimal vehicle scheduling solution, and the optimal criterion is proved via competitive analysis. A case study is carried out to evaluate the proposed methodology by using field data collected from one transit system.

Optimal Scheduling for Real-Time Jobs in Energy Harvesting Computing Systems

In this paper, we study a scheduling problem, in which every job is associated with a release time, deadline, required computation time, and required energy. We focus on an important special case where the jobs execute on a uniprocessor system that is supplied by a renewable energy source and use a rechargeable storage unit with limited capacity. Earliest deadline first (EDF) is a class one online algorithm in the classical real-time scheduling theory where energy constraints are not considered. We propose a semi-online EDF-based scheduling algorithm theoretically optimal (i.e., processing and energy costs neglected). This algorithm relies on the notions of energy demand and slack energy, which are different from the well known notions of processor demand and slack time. We provide an exact feasibility test. There are no restrictions on this new scheduler: each job can be one instance of a periodic, aperiodic, or sporadic task with deadline.

Composition of design patterns

This article deals with performance verification of architecture models of real-time embedded systems. We investigate scheduling analysis of multi-tasks applications running on real-time operating systems (RTOS in this article). Scheduling analysis on these types of system can be performed with the real-time scheduling theory, but applying it is a complicated task. To allow designer to automatically apply this theory, we propose several architectural design patterns. Each architectural design pattern models a classical task synchronization or communication protocol available in RTOSes. In this article, we focus on those design patterns composition. We show how to compose the proposed design patterns and how scheduling analysis can be run with them.

The Review of the Single Machine Scheduling Problem and its Solving Methods

The research on the theory and method of single machine scheduling is a difficult subject, but it is very important for the companies to improve the production efficiency and effectiveness. The study on single machine scheduling problem has the history of 50 years, but there is still a gap between the classical scheduling theories and practical scheduling problems. According to this characteristic, the problems in practical scheduling area and the various factors need to be concerned are mentioned, and the main methods to solving the single machine scheduling problem and their applications are presented in details. Finally, the directions and suggestions of future work in single machine scheduling problem are summarized.

Research on Integration of Information Flow and Logistics in VMI Based on TPL

The paper reviewed the relevant literature and research and summarized on VMI, inventory control and transportation scheduling theory ,VMI mode integrated inventory and transportation problem is analyzed theoretically the internal driving force and necessity and insufficiency of the supplier's logistics capabilities and information capabilities.from the systemic view,this dissertation deeply analyzed the information flow and logistics integration in VMI&TPL mode and achieved the predicted research objectives.

The Stability Studies of the Message Transmission in CAN Bus

The message transmission stability is very important for the design of the CAN bus system, which is related to the normal operation of the bus control system. The message transmission time is analyzed based on the Tindell scheduling theory, and the message transmission stability analysis is studied by means of probability analysis based on the second-moment method. An example in vehicle is calculated to get its message stability and the result is contrasted with the MONTE-CARLO method, and then the message transmission stability can be got using the method above; this will be the basis for calculating the stability of the CAN bus system, and provides the foundation for the further scheduling theory studies. It has great practical significe for CAN bus.

Modeling the Process of Animation Production

In this study, a work process model for animation production is developed. Interviews with animation studio workers and surveys of their working diaries and shot progress charts are conducted to create a framework for the work processes. The work hours necessary for each operation of the work project are expressed using a gamma function. Workers are classified into two categories, managers and animators, and their behavioral rules are modeled. To establish a rule for the determination of the operation sequence order for an animator to perform multiple work operations, four typical dispatching rules, often used in a scheduling theory, are selected, and the one that is closest to actual data is regarded as the rule that the animator actually follows. As a result of the analysis, it is found that the Earliest Due Date (EDD) and SLACK are closest to actual animators’ behavioral rules. Managers are also found to move the sub-deadline (a deadline of each operation) up about 30% earlier than the actual deadline. The knowledge we obtain is that, in order to realize better working conditions, animators should determine their operation sequence order by using SLACK, and managers should designate subdeadlines by keeping a balance between the prevention of deadline violation and the reduction of overtime work.