提出一个数据流反馈调度框架(Feedback scheduling framework for data flow,FSF-DF),该调度框架可以预防因数据流中断而导致全软件数控系统加工时间延长与加工质量降低的现象。FSF-DF在数据流上的缓存中设置溢出警戒线,并实时地监测缓...提出一个数据流反馈调度框架(Feedback scheduling framework for data flow,FSF-DF),该调度框架可以预防因数据流中断而导致全软件数控系统加工时间延长与加工质量降低的现象。FSF-DF在数据流上的缓存中设置溢出警戒线,并实时地监测缓存中的数据量是否超出溢出警戒线,以此判断数据流是否有发生数据中断的危险。在数据流将要中断时,调整相关任务的执行频率和优先级,以维持数控系统的稳定性。利用马尔可夫链等统计方法降低执行频率的调整次数,使得FSF-DF具有较低的系统开销。通过建立包括监视器、控制器与基本调度器在内的动态反馈调度框架,使得任务执行频率与优先级的调整规则能够有效地集成在实时操作系统中。在实时操作系统RTAI中实现了FSF-DF,并验证它的有效性。试验结果表明,数据流反馈调度框架可以有效地预防数控系统中的数据流中断现象,能够提高数控系统的整体性能与加工速度。展开更多
Due to the various performance requirements and data access restrictions of different types of real-time transactions, concurrency control protocols which had been designed for the systems with single type of transact...Due to the various performance requirements and data access restrictions of different types of real-time transactions, concurrency control protocols which had been designed for the systems with single type of transactions are not sufficient for mixed real-time database systems (MRTDBS), where different types of real-time transactions coexist in the systems concurrently. In this paper, a new concurrency control protocol MRTT_CC for mixed real-time transactions is proposed. The new strategy integrates with different concurrency control protocols to meet the deadline requirements of different types of real-time transactions. The data similarity concept is also explored in the new protocol to reduce the blocking time of soft real-time transactions, which increases their chances to meet the deadlines. Simulation experiments show that the new protocol has gained good performance.展开更多
文摘提出一个数据流反馈调度框架(Feedback scheduling framework for data flow,FSF-DF),该调度框架可以预防因数据流中断而导致全软件数控系统加工时间延长与加工质量降低的现象。FSF-DF在数据流上的缓存中设置溢出警戒线,并实时地监测缓存中的数据量是否超出溢出警戒线,以此判断数据流是否有发生数据中断的危险。在数据流将要中断时,调整相关任务的执行频率和优先级,以维持数控系统的稳定性。利用马尔可夫链等统计方法降低执行频率的调整次数,使得FSF-DF具有较低的系统开销。通过建立包括监视器、控制器与基本调度器在内的动态反馈调度框架,使得任务执行频率与优先级的调整规则能够有效地集成在实时操作系统中。在实时操作系统RTAI中实现了FSF-DF,并验证它的有效性。试验结果表明,数据流反馈调度框架可以有效地预防数控系统中的数据流中断现象,能够提高数控系统的整体性能与加工速度。
文摘Due to the various performance requirements and data access restrictions of different types of real-time transactions, concurrency control protocols which had been designed for the systems with single type of transactions are not sufficient for mixed real-time database systems (MRTDBS), where different types of real-time transactions coexist in the systems concurrently. In this paper, a new concurrency control protocol MRTT_CC for mixed real-time transactions is proposed. The new strategy integrates with different concurrency control protocols to meet the deadline requirements of different types of real-time transactions. The data similarity concept is also explored in the new protocol to reduce the blocking time of soft real-time transactions, which increases their chances to meet the deadlines. Simulation experiments show that the new protocol has gained good performance.
