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About 1,833 papers for “Dynamic priority scheduling”

Dynamic priorities, priority scheduling and priority inheritance

Fred Maymir-Ducharme · ACM SIGAda Ada Letters · 1990

Scheduling requirements are a major portion of the set of requirements that must be addressed by the Ada 9X Project. This is evident by the numerous Revision Requests (RRs) submitted (over 25) to the Ada 9X Project Office and the subsequent Revision Issues (RI-7005 and RI-7007). The related 9X requirements are: R1 - Flexible scheduling R2 - Flexible entry queue ordering IR2 - Rendezvous performance IR3 - Extended priority support WR1 - Flexible select algorithm This report summarizes the workshop's discussions on this important area. The discussions first considered dynamic priorities, and then priority scheduling and priority inheritance.

Cited by 2

Realization of dynamic priority scheduling algorithm

Cong Longshui · 2013

This paper introduces the scheduling of several basic algorithms and their advantages and disadvantages, the dynamic priority scheduling algorithm design of integrated several scheduling basic algorithm, and gives the realization plan. The study has great reference for various application of microcomputer based on cluster.

Cited by 0

Robust aperiodic scheduling under dynamic priority systems

Marco Spuri, Giorgio Buttazzo, F. Sensini · 2002

When hard periodic and firm aperiodic tasks are jointly scheduled in the same system, the processor workload can vary according to the arrival times of aperiodic requests. In order to guarantee the schedulability of the periodic task set, in overload conditions some aperiodic tasks must be rejected. In this paper we propose a technique that, in overload conditions, adds robustness to the joint scheduling of periodic and aperiodic tasks in systems with dynamic priorities. Our technique is based on an aperiodic server, called total bandwidth server, already proven effective in a previous work. Here the algorithm is first extended to efficiently handle firm aperiodic tasks and then integrated with a robust guarantee mechanism that allows to achieve graceful degradation in case of transient overloads. Extensive simulations show that the proposed new algorithm is effective in all workload conditions.

Cited by 101

Dynamic Multi Threshold Priority Packet Scheduling Algorithms

Tamer Dag, Sezer Uzungenc · Springer Link (Chiba Institute of Technology) · 2016

\nPacket scheduling algorithms are developed in order to use shared transmission resources efficiently. Various application packets such as real and non-real time packets might have different QoS requirements and traditional scheduling algorithms might be insufficient to respond to the applications needs. In this paper, two packet scheduling algorithms are proposed to overcome this problem: Dynamic multi threshold priority packet scheduling (DMTPS) and dynamic multi threshold priority with urgency packet scheduling (DMTPUS). The proposed algorithms aim to provide a better QoS level with a decrease in delay time and loss ratio for the low priority packets while still maintaining acceptable fairness towards high priority packets. To evaluate the performance of DMTPS and DMTPUS algorithms, they are compared with the commonly used scheduling algorithms such as first come first served (FCFS) and fixed priority. Simulation results illustrate that the dynamic multi threshold priority packet scheduling algorithms can provide a better QoS for low priority packets without decreasing the QoS levels of high priority packets.\n

Cited by 0

Optimal aperiodic scheduling for dynamic-priority systems

Ismael Ripoll, Ana García‐Fornes, Alfons Crespo · 2002

This paper addresses the problem of jointly scheduling tasks with both hard and soft real-time constraints. We present a new on-line aperiodic admission algorithm to be used with on optimal dynamic priority preemptive scheduler, such as the Earliest Deadline First (EDF) or the Least Laxity First (LLF). The admission algorithm transforms a soft aperiodic task into a hard one by assigning a deadline. The proposed algorithm is shown to be optimal in terms of providing the shortest response time for soft aperiodic tasks among fixed and dynamic priority schedulers (assuming aperiodic tasks are severed in a FCFS order), without endangering the execution of any periodic task. The paper also shows how the main results and ideas developed for the fixed priority theory can be adapted and extended for dynamic priority schedulers. The algorithm has also been extended to work with firm deadline aperiodic tasks.

Cited by 0

A Dynamic Priority-based Scheduling Method in

Distributed Systems Yongcheng, Yongcheng Li, Roy Campbell · 1995

A dynamic priority-based scheduling method (DPSM) is presented to improve the performance of client/server distributed systems.

Cited by 0

Dynamic Versus Fixed Priority Scheduling: A Case Study

Daniel I. Katcher, Jay K. Strosnider, Elizabeth A. Hinzelman-fortino · 1993

This paper demonstrates a formal, quantitative methodology for making engineering decisions on the construction and implementation of application specific, real-time operating systems. Specifically, we present the results of a case study comparing the relative viability of dynamic versus fixed priority schedulers within the context of the Mwave/OS operating system. Mwave/OS is being used in forthcoming products from IBM that will provide single board implementations of audio, video, facsimile, modems, MIDI, etc. to the PC marketplace. Scheduling models for both dynamic and fixed priority scheduling implementations for the Mwave/OS system are developed. The scheduling models include simple utilization-based tests that are suitable for on-line use, and more complex time-based tests. The complex, dynamic scheduling model is validated against the actual hardware and shown to be accurate to within 1%. The relative viability of the fixed vs dynamic priority scheduling for IBM's application i...

Cited by 0

Adaptive dynamic priority scheduling for virtual desktop infrastructures

Jinho Hwang, Timothy Wood · 2012

Virtual Desktop Infrastructures (VDIs) are gaining popularity in cloud computing by allowing companies to deploy their office environments in a virtualized setting instead of relying on physical desktop machines. Consolidating many users into a VDI environment can significantly lower IT management expenses and enables new features such as available-anywhere desktops. However, barriers to broad adoption include the slow performance of virtualized I/O, CPU scheduling interference problems, and shared-cache contention. In this paper, we propose a new soft real-time scheduling algorithm that employs flexible priority designations (via utility functions) and automated scheduler class detection (via hypervisor monitoring of user behavior) to provide a higher quality user experience. We have implemented our scheduler within the Xen virtualization platform, and demonstrate that the overheads incurred from co-locating large numbers of virtual machines can be reduced from 66% with existing schedulers to under 2% in our system. We evaluate the benefits and overheads of using a smaller scheduling time quantum in a VDI setting, and show that the average overhead time per scheduler call is on the same order as the existing SEDF and Credit schedulers.

Cited by 30

Dynamic Priority Approach for Unit Commitment Scheduling Solution

Fiqqih Faizah, Rifdian Indrianto Sudjoko, Mat Syai’in et al. · 2024

This paper introduces a dynamic priority approach (DPA) for solving unit commitment (UC) problems. The DPA is a novel technique introduced in this paper that is a development and simplification of the conventional priority list (PL) using the cumulative summation form of generating unit capacity. The conventional PL technique maximizes the previous unit’s capacity before adding the next one until the entire load is accommodated. According to the maximization focus of the unit capacity, the ramp rate is ignored so that the generation cost result sometimes cannot reach the optimal value. In this research, the proposed method is resolved in 2 main stages: the UC and economic dispatch (ED) stages. Prior to the main stage calculation, the technique begins with two initializations: initial available unit determination, considering the unit status in the last scheduling period, and the unit priority criteria factor calculation, considering fuel cost, startup cost, maximum generation limit, and ramp rate as the criteria factors. The UC stage consists of several phases, starting with the determination of unit availability status, prioritization of the available units based on the criteria factors, cumulative calculation of the unit’s maximum generation capacity according to the sorted available units, determination of base units based on the cumulative value index that can satisfy the load demand, and the base unit’s evaluation to re-evaluate the unit availability. These base units are the committed units that are optimized for load dispatching in the ED stage using particle swarm optimization (PSO). The ramp rate constraint was deliberated at both stages, as one of the priority criterion factors in UC and the boundary constraint in ED, expecting to minimize the overall generation cost. The performance of the proposed method was verified using a ten-unit test system whose results were compared with the previous related studies. The obtained results show that the proposed method provides effective and efficient scheduling results.

Cited by 1

Computer control : task synchronisation in dynamic priority scheduling

Sérgio F. Lopes, António José Pessoa de Magalhães · RepositóriUM (Universidade do Minho) · 1997

Due to common resource protection, most real-time tasks have non-preemptive sections. Such sections, called critical sections, rise several problems to real-time scheduling theory. Namely, deadlock avoidance and bounded blocking time. Different and widely mentioned solutions exist for this problem in the context of fixed priority scheduling. However, solutions for the same problem but in the context of totally dynamic scheduling, although much more interesting, are seldom referred in the current literature. This paper surveys those solutions and illustrates their philosophies, providing thus a considerable help for real-time systems designers who develop or intent to develop their applications upon EDF or other totally dynamic scheduling algorithm.

Cited by 0Open access

Dynamic Scheduling for Charging Electric Vehicles: A Priority Rule

Yunjian Xu, Feng Pan, Lang Tong · arXiv (Cornell University) · 2016

We consider the scheduling of multiple tasks with pre-determined deadlines under random processing cost. This problem is motivated by the potential of large scale adoption of plug-in (hybrid) electric vehicles (PHEVs) in the near future. The charging requests of PHEVs usually have deadline constraints, and the electricity cost associated with PHEV charging is usually random due to the uncertainty in both system load and renewable generation. We seek to properly schedule the battery charging of multiple PHEVs so as to minimize the overall cost, which is derived from the total charging cost and the penalty for not completing charging before requested deadlines. Through a dynamic programming formulation, we establish the Less Laxity and Longer remaining Processing time (LLLP) principle that improves any charging policy on a sample-path basis, when the non-completion penalty is a convex function of the additional time needed to fulfill the uncompleted request. Specifically, the LLLP principle states that priority should be given to vehicles that have less laxity and longer remaining processing times. Numerical results demonstrate that heuristic policies that violate the LLLP principle, for example, the earliest deadline first (EDF) policy, can result in significant performance loss.

Cited by 0Open access