实时任务调度器硬件化的设计与实现

硬件化的实时任务调度器使用VHDL语言进行编写,使用组合逻辑电路和时序逻辑电路实现基于优先级的时间片轮转调度算法。由门电路搭建而成的硬件化调度器独立于内核之外,根据连接内核的数量,在编译时进行调整,同时对多个结构相同或不同的内核进行调度。内核只需要执行任务,不需要进行任务调度,以此来减轻对处理器的负担,提升操作系统的实时性和可靠性。     

基于Vxworks的语音控制系统多任务调度算法的研究

研究了一种用于电力控制的基于Vxworks的语音控制系统的多任务调度算法,根据系统功能划分了任务及优先级,采用信号量通信方式,设计了时间片轮转和基于优先级抢占的混合调度算法,经仿真测试,算法运行效果稳定,任务切换时间达到毫秒级。     

基于ARM_Nucleus的气象数据采集系统的设计

以ARM7EJ—S微处理器的MT6226芯片为核心,阐述了在Nucleus实时操作系统下实现气象数据采集的设计方案。给出了硬件设计框图,同时根据气象数据的特点采用了优先级和时间片轮转法相结合的调度算法对系统任务进行划分,实现各种任务的并行执行,从而提高了资源的利用率,使整个系统运行更加稳定。     

温度感知的调度算法研究与实现

针对处理器的温度管理问题,在操作系统层次上提出一种轮转调度算法,改进基于门限温度的调度算法,并在Linux内核中实现了这两个算法.轮转调度算法有规律地让任务在双核上执行相等的时间,更好地平衡了处理器的温度,并且系统的吞吐量不受影响.     

进程调度策略在Linux中的实现

Linux是一个多用户多任务的操作系统。系统上所有运行的东西都可以称作进程。Linux把进程分为实时进程和非实时进程来处理,它采用时间片轮转和可剥夺调度优先级相结合的调度策略。详细介绍了实时进程和非实时进程在Linux不同进程调度中的应用。     

面向拟态云服务的异构执行体调度算法

针对当前异构调度模型仅从空间或者时间特性进行建模设计,缺少对时空特性的综合考虑且存在动态性和异构性不够均衡的问题。为使拟态云服务系统的动态、异构和冗余特性能够平衡互补,提出一种基于优先级和时间片的执行池调度算法,该算法基于执行池相似性指标进行优先级预排序,结合时间片等策略进行方案调度。实验结果表明,所提算法有较好的动态性,结合时间片策略能够获得动态性和异构性的综合平衡,且算法耗时较低。     

一种基于Vxworks的多任务调度算法

针对机载二次配电系统(the Second Power Distribution Association,缩写为SPDA)的任务调度,提出了一种选择时间片轮转与静态权重优先级抢占混合的调度算法,并进行了算法仿真.     

基于VxWorks的多任务程序设计及通信管理

为了满足系统各个任务对实时性的要求,需要实现各个任务的并行处理。针对VxWorks操作系统的多任务调度机制和任务通信方式进行了分析;采用基于时间片轮转调度实现多任务程序设计,可以动态改变各个任务期望运行的时间片;对各种通信方式和实现方法进行了比对,并给出了优化方案。上述设计方法实时性强,可靠性高,系统可扩展性良好,能够很好地满足工程需要。     

微内核结构嵌入式实时操作系统的研究与设计

分析了微内核结构在设计嵌入式实时操作系统时的优点,设计了一个微内核结构的嵌入式实时操作系统,整个系统内核由任务管理、任务通信、时钟管理、中断管理、内存管理等模块组成.内核采用抢占式调度和分时调度相结合的调度策略,以及基于查表法的优先级队列管理,使得系统在进行任务调度时能快速的找到所要调度的任务,满足实时性的要求.内核提供多种通信方式,并对控制临界资源访问的信号量进行了特别的设计,便于任务在必要的时候进行优先级继承,很好地解决了抢占式嵌入式操作系统中普遍存在的优先级反转问题.最后,在基于ARM处理器的EL-ARM-830硬件平台,给出了系统的实现.     

一种基于Vxworks的多任务调度算法

实时操作系统的任务调度算法是研究嵌入式系统开发的热点。针对机载二次配电系统（the Second Power Discribution Association,缩写为sPDA）的任务调度．提出了一种在信号量通信的基础上选择时间片轮转的静态权重优先级抢占混合的调度算法,并对算法进行了仿算。     

UbiFOS: A Small Real‐Time Operating System for Embedded Systems

The ubiquitous flexible operating system (UbiFOS) is a real‐time operating system designed for cost‐conscious, low‐power, small to medium‐sized embedded systems such as cellular phones, MP3 players, and wearable computers. It offers efficient real‐time operating system services like multi‐task scheduling, memory management, inter‐task communication and synchronization, and timers while keeping the kernel size to just a few to tens of kilobytes. For flexibility, UbiFOS uses various task scheduling policies such as cyclic time‐slice (round‐robin), priority‐based preemption with round‐robin, priority‐based preemptive, and bitmap. When there are less than 64 tasks, bitmap scheduling is the best policy. The scheduling overhead is under 9 µs on the ARM926EJ processor. UbiFOS also provides the flexibility for user to select from several inter‐task communication techniques according to their applications. We ported UbiFOS on the ARM9‐based DVD player (20 kB), the Calm16‐based MP3 player (under 7 kB), and the ATmega128‐based ubiquitous sensor node (under 6 kB). Also, we adopted the dynamic power management (DPM) scheme. Comparative experimental results show that UbiFOS could save energy up to 30% using DPM.     

一种基于风险感知策略的多节点任务调度方法

为解决无人机(UAV)集群任务调度时面临各节点动态、不稳定的情况,该文提出一种面向多计算节点的可尽量避免任务中断且具有容错性的任务调度方法。该方法首先为基于多计算节点构建了一个以最小化任务平均完成时间为优化目标的任务分配策略;然后基于任务的完成时间和边缘计算节点的存留时间两者的概率分布,将任务计算节点上的执行风险量化成额外开销时间;最后以任务的完成时间与额外开销时间之和替换原本的完成时间,设计了风险感知的任务分配策略。在仿真环境下将该文提出的任务调度方法与3种基准调度方法进行了对比实验,实验结果表明该方法能够有效地降低任务平均响应时间、任务平均执行次数以及任务截止时间错失率。证明该文提出的方法降低了任务重调度和重新执行带来的额外开销,可实现分布式协同计算任务的调度工作,为复杂场景下的无人机集群网络提供新的技术支持。     

Network real-time scheduling algorithm based on multi-feature dynamic priority

Real-time task scheduling system structure and task model were proposed aiming at the network real-time scheduling problem.The task degree of urgency was defined by considering the deadline of task,execution time and interval time between works.The task degree of tightness was proposed based on service-level assurance,according to functional importance of different tasks in the real-time task scheduling system.The thrashing limit for avoiding task switching frequently was acquired through dynamic regulation to task priorities by degree of urgency and degree of tightness,which guaranteed the success rate of tasks execution and utilization ratio of client execution.Test simulation results suggest that the multi-feature dynamic priority scheduling strategy improves the success rate of task scheduling and shorten the average response time,which suggests it has obvious superiority compared with BE and EDF scheduling algorithm.     

基于3D碎裂度布局策略的可重构硬件任务调度算法

现有硬件任务调度算法任务描述不完善且忽视时间维上紧凑性。该文考虑任务下载时间、完善任务属性,以器件2维资源与时间建立3维资源模型,将任务布局问题抽象成特殊的3维空间放置问题,在此模型上分析出现有算法不能克服任务不可预知性和资源占用多变性,导致调度成功率和资源利用率低。针对此问题,该文提出了一种3维可重构任务调度算法3D_RTSA。设计并实现了基于任务紧迫度的调度策略和基于3D碎裂度的布局策略。与其他4种算法实验对比结果表明,在重负载、小任务C30情况下,3D_RTSA调度成功率比GC, Look-aheadest, SPSA, DTI算法分别高3%, 21%, 28%, 35%左右;在轻负载、大任务C50情况下,资源利用率比Look-aheadest, SPSA算法分别高5%, 18%左右,且该文算法时间复杂度并未增加。     

Kernel Thread Scheduling in Real‐Time Linux for Wearable Computers

In Linux, real‐time tasks are supported by separating real‐time task priorities from non‐real‐time task priorities. However, this separation of priority ranges may not be effective when real‐time tasks make the system calls that are taken care of by the kernel threads. Thus, Linux is considered a soft real‐time system. Moreover, kernel threads are configured to have static priorities for throughputs. The static assignment of priorities to kernel threads causes trouble for real‐time tasks when real‐time tasks require kernel threads to be invoked to handle the system calls because kernel threads do not discriminate between real‐time and non‐real‐time tasks. We present a dynamic kernel thread scheduling mechanism with weighted average priority inheritance protocol (PIP), a variation of the PIP. The scheduling algorithm assigns proper priorities to kernel threads at runtime by monitoring the activities of user‐level real‐time tasks. Experimental results show that the algorithms can greatly improve the unexpected execution latency of real‐time tasks.     

基于嵌入式实时操作系统μC/OS-Ⅱ的多任务算法研究

μC/OS-Ⅱ是一个高度简洁、可固化、可裁剪、实现抢先式实时多任务的操作系统内核。而嵌入式软件系统的一个重要特征是实时响应和多任务处理。本文首先简要介绍了μC/OS-Ⅱ及其μC/OS-Ⅱ在应用系统软件的设计中的任务状态和任务调度。基于集成开发环境IAREWARM,提出了一种基于μC/OS-Ⅱ的多任务调度算法以实现＂欢迎使用＂的衡定时间交替显示的功能,着重介绍了μC/OS-Ⅱ中多任务间的切换和调度的实现机理。μC/OS-Ⅱ作为一个精简、可靠的多任务操作系统,在中小型工业领域中有着广泛的应用前景。     

A non‐cooperative game model for reliability‐based task scheduling in cloud computing

Cloud computing is a newly emerging distributed system. Task scheduling is the core research of cloud computing which studies how to allocate the tasks among the physical nodes, so that the tasks can get a balanced allocation or each task's execution cost decreases to the minimum, or the overall system performance is optimal. Unlike task scheduling based on time or cost before, aiming at the special reliability requirements in cloud computing, we propose a non‐cooperative game model for reliability‐based task scheduling approach. This model takes the steady‐state availability that computing nodes provide as the target, takes the task slicing strategy of the schedulers as the game strategy, then finds the Nash equilibrium solution. We also design a task scheduling algorithm based on this model. It can be seen from the experiments that our task scheduling algorithm is better than the so‐called balanced scheduling algorithm.     

一种云计算环境下任务调度策略

文章提出的问题是在云计算环境下任务调度策略。该策略的目标是将任务分配到计算单元上达到任务完成总时间最少和资源充分利用。基于此目标文章提出利用遗传算法对任务完成时间进行优化,并为处于空闲状态计算单元动态调整任务分配以改善资源利用率。利用CloudSim仿真平台验证该方法的有效性。