Topic
Scheduling (computing)
About: Scheduling (computing) is a research topic. Over the lifetime, 78638 publications have been published within this topic receiving 1341254 citations. The topic is also known as: sched & schedule.
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TL;DR: This self-contained paper develops the theory necessary to statically schedule SDF programs on single or multiple processors, and a class of static (compile time) scheduling algorithms is proven valid, and specific algorithms are given for scheduling SDF systems onto single ormultiple processors.
Abstract: Large grain data flow (LGDF) programming is natural and convenient for describing digital signal processing (DSP) systems, but its runtime overhead is costly in real time or cost-sensitive applications. In some situations, designers are not willing to squander computing resources for the sake of programmer convenience. This is particularly true when the target machine is a programmable DSP chip. However, the runtime overhead inherent in most LGDF implementations is not required for most signal processing systems because such systems are mostly synchronous (in the DSP sense). Synchronous data flow (SDF) differs from traditional data flow in that the amount of data produced and consumed by a data flow node is specified a priori for each input and output. This is equivalent to specifying the relative sample rates in signal processing system. This means that the scheduling of SDF nodes need not be done at runtime, but can be done at compile time (statically), so the runtime overhead evaporates. The sample rates can all be different, which is not true of most current data-driven digital signal processing programming methodologies. Synchronous data flow is closely related to computation graphs, a special case of Petri nets. This self-contained paper develops the theory necessary to statically schedule SDF programs on single or multiple processors. A class of static (compile time) scheduling algorithms is proven valid, and specific algorithms are given for scheduling SDF systems onto single or multiple processors.
1,380 citations
TL;DR: In this paper, the minimum throughput over all ground users in the downlink communication was maximized by optimizing the multiuser communication scheduling and association jointly with the UAV's trajectory and power control.
Abstract: Due to the high maneuverability, flexible deployment, and low cost, unmanned aerial vehicles (UAVs) have attracted significant interest recently in assisting wireless communication. This paper considers a multi-UAV enabled wireless communication system, where multiple UAV-mounted aerial base stations are employed to serve a group of users on the ground. To achieve fair performance among users, we maximize the minimum throughput over all ground users in the downlink communication by optimizing the multiuser communication scheduling and association jointly with the UAV’s trajectory and power control. The formulated problem is a mixed integer nonconvex optimization problem that is challenging to solve. As such, we propose an efficient iterative algorithm for solving it by applying the block coordinate descent and successive convex optimization techniques. Specifically, the user scheduling and association, UAV trajectory, and transmit power are alternately optimized in each iteration. In particular, for the nonconvex UAV trajectory and transmit power optimization problems, two approximate convex optimization problems are solved, respectively. We further show that the proposed algorithm is guaranteed to converge. To speed up the algorithm convergence and achieve good throughput, a low-complexity and systematic initialization scheme is also proposed for the UAV trajectory design based on the simple circular trajectory and the circle packing scheme. Extensive simulation results are provided to demonstrate the significant throughput gains of the proposed design as compared to other benchmark schemes.
1,361 citations
TL;DR: In this article, an extension of deterministic sequencing and scheduling problems, in which the jobs require the use of additional scarce resources during their execution, is considered, and a classification scheme for resource constraints is proposed and the computational complexity of the extended problem class is investigated.
1,297 citations
Patent•
04 Apr 2001
TL;DR: In this article, a software scheduling agent is part of a probabilistic modeling system in which the scheduler operates to perform constrained random variation with selection, and the comparison and determination of which items of digital content should be offered for presentation to which users is performed by a process of constrained random variations.
Abstract: A method and apparatus wherein a software scheduling agent resides on a communication network and/or client device, such as location-aware wireless communication appliances, television set top boxes, or other end user client devices is disclosed. The software scheduling agent is part of a probabilistic modeling system in which the scheduler operates to perform constrained random variation with selection. Digital content is generated, organized, and stored on the communication network and/or the client devices. An electronic digital content wrapper, which holds information in the form of data and metadata related to the digital content is associated with each item of digital content. Contextual profiles for each user and each item of digital content are established by the users and the network and maintained by a service provider on the communication network. The software scheduling agent compares the contextual digital content profile for each item of digital content to the contextual user profile for each user to determine which digital content should be offered for presentation to each user. The comparison and determination of which items of digital content should be offered for presentation to which users is performed by a process of constrained random variation. After the software scheduling agent determines which items of digital content would most likely be relevant or interesting to the user, the digital content is transmitted, either in whole or in part, at predetermined times over the communication network to the appropriate client devices. The digital content is then stored, either in whole or in part, in cache memory on the client device until an appropriate time when the digital content is digitally packaged and presented to particular users over those user's client devices.
1,279 citations
TL;DR: This paper presents a scheduling algorithm called iSLIP, an iterative, round-robin algorithm that can achieve 100% throughput for uniform traffic, yet is simple to implement in hardware, and describes the implementation complexity of the algorithm.
Abstract: An increasing number of high performance internetworking protocol routers, LAN and asynchronous transfer mode (ATM) switches use a switched backplane based on a crossbar switch. Most often, these systems use input queues to hold packets waiting to traverse the switching fabric. It is well known that if simple first in first out (FIFO) input queues are used to hold packets then, even under benign conditions, head-of-line (HOL) blocking limits the achievable bandwidth to approximately 58.6% of the maximum. HOL blocking can be overcome by the use of virtual output queueing, which is described in this paper. A scheduling algorithm is used to configure the crossbar switch, deciding the order in which packets will be served. Previous results have shown that with a suitable scheduling algorithm, 100% throughput can be achieved. In this paper, we present a scheduling algorithm called iSLIP. An iterative, round-robin algorithm, iSLIP can achieve 100% throughput for uniform traffic, yet is simple to implement in hardware. Iterative and noniterative versions of the algorithms are presented, along with modified versions for prioritized traffic. Simulation results are presented to indicate the performance of iSLIP under benign and bursty traffic conditions. Prototype and commercial implementations of iSLIP exist in systems with aggregate bandwidths ranging from 50 to 500 Gb/s. When the traffic is nonuniform, iSLIP quickly adapts to a fair scheduling policy that is guaranteed never to starve an input queue. Finally, we describe the implementation complexity of iSLIP. Based on a two-dimensional (2-D) array of priority encoders, single-chip schedulers have been built supporting up to 32 ports, and making approximately 100 million scheduling decisions per second.
1,277 citations