Scheduling for today’s computer systems: bridging theory and practice

Scheduling is a fundamental technique for improving performance in computer systems. From web servers to routers to operating systems, how the bottleneck device is scheduled has an enormous impact on the performance of the system as a whole. Given the immense literature studying scheduling, it is easy to think that we already understand enough about scheduling. But, modern computer system designs have highlighted a number of disconnects between traditional analytic results and the needs of system designers. In particular, the idealized policies, metrics, and models used by analytic researchers do not match the policies, metrics, and scenarios that appear in real systems. The goal of this thesis is to take a step towards modernizing the theory of scheduling in order to provide results that apply to today’s computer systems, and thus ease the burden on system designers. To accomplish this goal, we provide new results that help to bridge each of the disconnects mentioned above. We will move beyond the study of idealized policies by introducing a new analytic framework where the focus is on scheduling heuristics and techniques rather than individual policies. By moving beyond the study of individual policies, our results apply to the complex hybrid policies that are often used in practice. For example, our results enable designers to understand how the policies that favor small job sizes are affected by the fact that real systems only have estimates of job sizes. In addition, we move beyond the study of mean response time and provide results characterizing the distribution of response time and the fairness of scheduling policies. These results allow us to understand how scheduling affects QoS guarantees and whether favoring small job sizes results in large job sizes being treated unfairly. Finally, we move beyond the simplified models traditionally used in scheduling research and provide results characterizing the effectiveness of scheduling in multiserver systems and when users are interactive. These results allow us to answer questions about the how to design multiserver systems and how to choose a workload generator when evaluating new scheduling designs

Proceedings of the 26th International Symposium on Theoretical Aspects of Computer Science (STACS'09)

The Symposium on Theoretical Aspects of Computer Science (STACS) is held alternately in France and in Germany. The conference of February 26-28, 2009, held in Freiburg, is the 26th in this series. Previous meetings took place in Paris (1984), Saarbr¨ucken (1985), Orsay (1986), Passau (1987), Bordeaux (1988), Paderborn (1989), Rouen (1990), Hamburg (1991), Cachan (1992), W¨urzburg (1993), Caen (1994), M¨unchen (1995), Grenoble (1996), L¨ubeck (1997), Paris (1998), Trier (1999), Lille (2000), Dresden (2001), Antibes (2002), Berlin (2003), Montpellier (2004), Stuttgart (2005), Marseille (2006), Aachen (2007), and Bordeaux (2008). ..

A vision-based optical character recognition system for real-time identification of tractors in a port container terminal

Automation has been seen as a promising solution to increase the productivity of modern sea port container terminals. The potential of increase in throughput, work efficiency and reduction of labor cost have lured stick holders to strive for the introduction of automation in the overall terminal operation. A specific container handling process that is readily amenable to automation is the deployment and control of gantry cranes in the container yard of a container terminal where typical operations of truck identification, loading and unloading containers, and job management are primarily performed manually in a typical terminal. To facilitate the overall automation of the gantry crane operation, we devised an approach for the real-time identification of tractors through the recognition of the corresponding number plates that are located on top of the tractor cabin. With this crucial piece of information, remote or automated yard operations can then be performed. A machine vision-based system is introduced whereby these number plates are read and identified in real-time while the tractors are operating in the terminal. In this paper, we present the design and implementation of the system and highlight the major difficulties encountered including the recognition of character information printed on the number plates due to poor image integrity. Working solutions are proposed to address these problems which are incorporated in the overall identification system.postprin

Proactive-reactive, robust scheduling and capacity planning of deconstruction projects under uncertainty

A project planning and decision support model is developed and applied to identify and reduce risk and uncertainty in deconstruction project planning. It allows calculating building inventories based on sensor information and construction standards and it computes robust project plans for different scenarios with multiple modes, constrained renewable resources and locations. A reactive and flexible planning element is proposed in the case of schedule infeasibility during project execution

Artificial Intelligence Models for Scheduling Big Data Services on the Cloud

The widespread adoption of Internet of Things (IoT) applications in many critical sectors (e.g., healthcare, unmanned autonomous systems, etc.) and the huge volumes of data that are being generated from such applications have led to an unprecedented reliance on the cloud computing platform to store and process these data. Moreover, cloud providers tend to receive massive waves of demands on their storage and computing resources. To help providers deal with such demands without sacrificing performance, the concept of cloud automation had recently arisen to improve the performance and reduce the manual efforts related to the management of cloud computing workloads. However, several challenges have to be taken into consideration in order to guarantee an optimal performance for big data storage and analytics in cloud computing environments. In this context, we propose in this thesis a smart scheduling model as an automated big data task scheduling approach in cloud computing environments. Our scheduling model combines Deep Reinforcement Learning (DRL), Federated Learning (FL), and Transfer Learning (TL) to automatically predict the IoT devices to which each incoming big data task should be scheduled to as to improve the performance and reduce the execution cost. Furthermore, we solve the long execution time and data shortage problems by introducing a FL-based solution that also ensures privacy-preserving and reduces training and data complexity. The motivation of this thesis stems from four main observations/research gaps that we have drawn through our literature reviews and/or experiments, which are: (1) most of the existing cloud-based scheduling solutions consider the scheduling problem only from the tasks priority viewpoint, which leads to increase the amounts of wasted resources in case of malicious or compromised IoT devices; (2) the existing scheduling solutions in the domain of cloud and edge computing are still ineffective in making real-time decisions concerning the resource allocation and management in cloud systems; (3) it is quite difficult to schedule tasks or learning models from servers in areas that are far from the objects and IoT devices, which entails significant delay and response time for the process of transmitting data; and (4) none of the existing scheduling solutions has yet addressed the issue of dynamic task scheduling automation in complex and large-scale edge computing settings. In this thesis, we address the scheduling challenges related to the cloud and edge computing environment. To this end, we argue that trust should be an integral part of the decision-making process and therefore design a trust establishment mechanism between the edge server and IoT devices. The trust mechanism model aims to detect those IoT devices that over-utilize or under-utilize their resources. Thereafter, we design a smart scheduling algorithm to automate the process of scheduling large-scale workloads onto edge cloud computing resources while taking into account the trust scores, task waiting time, and energy levels of the IoT devices to make appropriate scheduling decisions. Finally, we apply our scheduling strategy in the healthcare domain to investigate its applicability in a real-world scenario (COVID-19)