發(fā)布時(shí)間：2018-03-24 17:54

  本文選題：多核平臺(tái)　切入點(diǎn)：混合任務(wù)　出處：《武漢理工大學(xué)》2013年碩士論文

【摘要】：隨著人類對(duì)計(jì)算機(jī)性能需求的不斷提高,處理具有嚴(yán)格時(shí)間限制的計(jì)算密集型實(shí)時(shí)應(yīng)用時(shí),單核處理器已經(jīng)顯得力不從心,人們把提高計(jì)算機(jī)性能的需求通過(guò)采用多核處理器來(lái)實(shí)現(xiàn)。目前,智能手機(jī)、平板電腦、筆記本電腦等電子產(chǎn)品基本上都采用了多核處理器。多核處理器因其諸多的優(yōu)勢(shì)將取代傳統(tǒng)的單核處理器,逐步成為市場(chǎng)的主流。 多核處理器的普及為實(shí)時(shí)系統(tǒng)的應(yīng)用提供了更廣闊的平臺(tái),也使實(shí)時(shí)系統(tǒng)變得更為復(fù)雜,系統(tǒng)中同時(shí)存在多種類型的任務(wù),其中主要包括硬實(shí)時(shí)周期任務(wù)和軟實(shí)時(shí)非周期任務(wù)兩種任務(wù)類型。這類實(shí)時(shí)混合任務(wù)調(diào)度目標(biāo)是在保證硬實(shí)時(shí)周期任務(wù)滿足截止期的前提下,盡量提高軟實(shí)時(shí)非周期任務(wù)的平均響應(yīng)時(shí)間,然而,這并不是唯一的目標(biāo),為了充分利用多核的性能優(yōu)勢(shì)以及維持系統(tǒng)的穩(wěn)定性,還需要考慮提高多核處理器的利用率和負(fù)載均衡。 針對(duì)以上兩個(gè)目標(biāo),本文對(duì)多核平臺(tái)的實(shí)時(shí)混合任務(wù)調(diào)度算法進(jìn)行了研究,主要工作如下： (1)首先,采用劃分方案將所有的硬實(shí)時(shí)周期任務(wù)映射到特定的處理器核上；然后,對(duì)每個(gè)核上的周期任務(wù)進(jìn)行分析,定義了“超周期空閑時(shí)間”和“空閑率”及相關(guān)計(jì)算方法,提出了分配最小截止期(Assign Minimum Deadline, AMD)算法,該算法為混合任務(wù)中的軟實(shí)時(shí)任務(wù)選擇具有最大空閑率的處理器核,并為其分配最小截止期；最后,將分配最小截止期的軟實(shí)時(shí)任務(wù)和硬實(shí)時(shí)周期任務(wù)一起由EDF算法進(jìn)行調(diào)度,可使混合任務(wù)中的軟實(shí)時(shí)任務(wù)盡可能早得到響應(yīng),從而有效縮短了軟實(shí)時(shí)任務(wù)的平均響應(yīng)時(shí)間,并且該算法利用的是周期任務(wù)集在每個(gè)超周期內(nèi)提供的空閑時(shí)間來(lái)處理軟實(shí)時(shí)任務(wù),所以不會(huì)影響到硬實(shí)時(shí)周期任務(wù)的截止期。 (2)硬實(shí)時(shí)周期任務(wù)的分配策略不僅會(huì)影響到軟實(shí)時(shí)任務(wù)的調(diào)度,還會(huì)影響到多核處理器的利用率及負(fù)載均衡(Utilization and Load Balance，，ULB),為了綜合考慮實(shí)時(shí)混合任務(wù)調(diào)度以及多核處理器的利用率和負(fù)載均衡,提出了EDF-ULB算法,該算法通過(guò)定義“分配因子”對(duì)周期任務(wù)集的分配策略進(jìn)行靈活選擇,實(shí)驗(yàn)結(jié)果表明,該算法在提高混合任務(wù)中軟實(shí)時(shí)任務(wù)平均響應(yīng)時(shí)間的同時(shí),有效的平衡了多核處理器核的高利用率和負(fù)載均衡。
[Abstract]:With the increasing demand for computer performance, when dealing with computationally intensive real-time applications with strict time constraints, the single-core processor has become inadequate. The need to improve the performance of computers is achieved through the use of multi-core processors. At present, smartphones, tablets, Notebook computers and other electronic products basically use multi-core processors. Because of its many advantages, multi-core processors will replace the traditional single-core processors and gradually become the mainstream of the market. The popularity of multi-core processors provides a broader platform for the application of real-time systems, and also makes real-time systems more complex, and there are many types of tasks in the system. There are two kinds of tasks: hard real-time periodic task and soft real time aperiodic task. The scheduling goal of this kind of real-time hybrid task is to ensure that hard real-time periodic task meets the deadline. To maximize the average response time of soft real-time aperiodic tasks, however, this is not the only goal, in order to take full advantage of the performance advantages of multi-core and maintain the stability of the system. Consideration should also be given to increasing the utilization and load balancing of multi-core processors. Aiming at the above two objectives, this paper studies the real-time hybrid task scheduling algorithm of multi-core platform. The main work is as follows:. First of all, all hard real-time periodic tasks are mapped to specific processor cores by partitioning scheme, then the periodic tasks on each core are analyzed, and the "super-period idle time", "idle rate" and the related calculation methods are defined. In this paper, an assign Minimum deadline (AMD) algorithm is proposed. The algorithm selects processor cores with maximum idle rate for soft real-time tasks in hybrid tasks, and assigns minimum deadlines to them. The soft real-time task with the minimum deadline is scheduled by EDF algorithm together with the hard real-time periodic task, so that the soft real-time task in the mixed task can be responded as early as possible, and the average response time of the soft real time task can be shortened effectively. Moreover, the algorithm uses the idle time provided by the periodic task set in each super-period to process soft real-time tasks, so it does not affect the deadline of hard real-time periodic tasks. The allocation strategy of hard real-time periodic tasks will not only affect the scheduling of soft real-time tasks. It will also affect the utilization of multi-core processors and load balancing. In order to comprehensively consider the real-time mixed task scheduling, the utilization and load balancing of multi-core processors, a EDF-ULB algorithm is proposed. The algorithm flexibly selects the allocation strategy of periodic task set by defining "assignment factor". The experimental results show that the algorithm not only improves the average response time of soft real-time tasks in hybrid tasks, but also increases the average response time of soft real-time tasks. The high utilization and load balance of multi-core processor core are effectively balanced.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TP301.6

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