Ethernet as the most popular technology of local-area network, has the advantages of fast speed, low-cost, convenience of installation and good compatibility, but since it exploits CSMA/CD as the MAC protocol, whichre...Ethernet as the most popular technology of local-area network, has the advantages of fast speed, low-cost, convenience of installation and good compatibility, but since it exploits CSMA/CD as the MAC protocol, whichresults in the "uncertainty" of data communication, it cannot be applicable to real-time communication fields, such asindustry automated control. This paper presents a hard real-time communication technique based on Ethernet namedARTC, which has well-formed architecture and is easy to be implemented, at the same time, there is no need of mod-ifying the hardware of Ethernet. ARTC utilizes the methods of command/response multiple transmission and bustable to allot low-level communication bandwidth. It supports station management, on-line participation and automat-ic generation of bus table. ARTC, which is oriented to message, also provides the guarantee of hard real-time com-munication and has characteristics of reliability and fine extensibility.展开更多
uClinux嵌入式操作系统具有优良的稳定性和网络功能,然而其不支持硬实时任务的缺陷却极大地限制了它在高实时性监控领域的应用。介绍了嵌入式实时操作系统在电能质量监控领域中的应用,以及uClinux系统的特性。利用实时应用接口RTAI(Real...uClinux嵌入式操作系统具有优良的稳定性和网络功能,然而其不支持硬实时任务的缺陷却极大地限制了它在高实时性监控领域的应用。介绍了嵌入式实时操作系统在电能质量监控领域中的应用,以及uClinux系统的特性。利用实时应用接口RTAI(Real Time Application Interface)对uClinux系统的实时性进行了扩展,采用对内核进行小规模改动的双内核方法实现Linux系统硬实时特性。对比实验可见RTAI/uClinux双内核系统具有良好的实时性能。展开更多
基金the National Natural Science Foundation of China under Grant Nos.60603032,60604029(国家自然科学基金)the NSFC-Guangdong Province of China under Grant No.U0735003(国家自然科学基金委-广东省联合基金重点项目)
文摘针对当前弱硬实时调度算法无法保证超过窗口长度的执行序列的满足率达到一定比例的问题,基于(m^-,p)弱硬实时约束,提出了一种基于裁剪的调度算法(cut-down based scheduling,简称CDBS).由于判断(m^-,p)约束是否满足需要遍历任务的整个执行序列,因此判断复杂度很大.为此,提出一种高效的裁剪执行序列的算法,同时证明其正确性,并利用适当的数据结构,使得计算复杂度与序列长度无关,通过实验说明其降低计算复杂度的有效性.进一步与其他经典实时调度算法(EDF(earliest deadline first),DBP(distance-based priority),DWCS(dynamic window constraint schedule))进行比较,验证该算法与其他算法具有相当的性能.
文摘Ethernet as the most popular technology of local-area network, has the advantages of fast speed, low-cost, convenience of installation and good compatibility, but since it exploits CSMA/CD as the MAC protocol, whichresults in the "uncertainty" of data communication, it cannot be applicable to real-time communication fields, such asindustry automated control. This paper presents a hard real-time communication technique based on Ethernet namedARTC, which has well-formed architecture and is easy to be implemented, at the same time, there is no need of mod-ifying the hardware of Ethernet. ARTC utilizes the methods of command/response multiple transmission and bustable to allot low-level communication bandwidth. It supports station management, on-line participation and automat-ic generation of bus table. ARTC, which is oriented to message, also provides the guarantee of hard real-time com-munication and has characteristics of reliability and fine extensibility.
文摘uClinux嵌入式操作系统具有优良的稳定性和网络功能,然而其不支持硬实时任务的缺陷却极大地限制了它在高实时性监控领域的应用。介绍了嵌入式实时操作系统在电能质量监控领域中的应用,以及uClinux系统的特性。利用实时应用接口RTAI(Real Time Application Interface)对uClinux系统的实时性进行了扩展,采用对内核进行小规模改动的双内核方法实现Linux系统硬实时特性。对比实验可见RTAI/uClinux双内核系统具有良好的实时性能。
