基于Linux的窗口约束QoS实时系统的研究
|
摘要
实时系统具有及时响应、高可靠性、专用性、少人工干预等特征,最初应用于军事和工业控制领域。而随着计算机技术和互联网技术的高速发展,实时技术被越来越多地应用于实时网络传输、视频传输、多媒体处理等软实时系统中。这类实时系统既不同于硬性规定作业完成时限的硬实时系统,也不同于没有详细规定任务应满足何种约束的软实时系统。这些新的应用都有一定的服务质量(QoS)需求,既有实时性的需求,又有丢失率方面的需求。由于这些新的特点,传统静态硬实时系统和基于公平调度的通用操作系统已经无法满足这类实际应用的需要。同时窗口约束理论由于在描述QoS特性上具有概率约束无法比拟的优点,近年来得到了广大学者的研究和广泛关注。
基于上述背景,本文结合开源的Linux系统,通过在其上引入窗口约束描述的QoS机制,采用合适的调度机制来满足弱硬实时系统的需求,与此同时开展了以下的研究:
1)在研究基于窗口约束(m,k)模型的实时系统的基础上,给出了一种组合窗口约束(m,k)∧＜(?),k＞的实时系统,并针对其给出了一种新的组合窗口约束的调度算法,该算法充分利用组合约束的特点,考虑本次调度对该窗口的可调度的影响来确定任务的优先级,并以此来提高任务的可调度性、减少组合窗口限制违例。仿真试验表明该算法在组合窗口约束的调度上,优于传统的独立比较两个约束确定优先级的调度算法;
2)结合组合窗口约束描述任务QoS更准确和便于调度算法设计的优点,同时针对标准Linux内核只提供三种调度策略:SCHED__RR、SCHED__FIFO、SCHED__OTHER,它们是无法实现具有QoS要求的任务调度的缺陷。本文通过可加载模块的方法,修改schedule()的调度策略,给出了组合窗口约束调度在Linux内核上的具体实现框架。
The real-time system has characters such as response in time, high dependability, dedication and less artificial interference, it was used initially applied to the field of military and industrial control. However, with the rapid development of computer and internet technology, real-time technology has been applied more and more to soft real-time system (SRTS), such as real-time network transmission, video transmission and multimedia processing. This SRTS is different from hard real-time systems that mandatory limit the deadline of jobs, and different from some soft real-time systems that don't make exactly rules for jobs. These new applications have a certain quality of service (QoS) requirements, which need satisfy the deadlines and loss-tolerance for jobs. As a result of these new features, Traditional static real-time systems and common operation system that based on fair scheduling can't satisfy these new applications. At the same time, window theory of constraints have incomparable advantages than probability constraints in describing QoS, it receives the majority of scholars research andextensive attention in recent years.
Based on the above background, this dissertation imports a QoS mechanism which described by window constraints into Linux kernel and uses a suitable scheduler for satisfying weakly hard real-time systems demands. And then contents about this were studied:
1) Based on the research of window-constrained real-time system with (m,k) constraints, a non-overlapping assembled window-constrained real-time system with (m, k)(?) constraints is proposed. By the research on schedulability of this real-time system, a new assembled window-constrained scheduling (AWCS) algorithm is prompted. The AWCS takes full advantage of the peculiarity of assembled constraints, and allocates the priority considering the affection of this scheduling for the total window, which improves the schedulability and reduces the violations of assembled window constraints. The simulation shows the AWCS is better than general algorithms that allocate priority by comparing these constraints independently.
2) Combining the advantages of assembled window-constraints in exactly describing Qos and designing scheduler. And for the bugs of standard Linux kernel only can supply three schedulers: SCHED_RR, SCHED_FIFOandSCHED_OTHER, which can't satisfy tasks' QoS. By using the method of lodable kernel model (LKM), this dissertation revised schedule()'s strategy, and give a concrete realization of the framework for AWCS in Linux kernel.
基于上述背景,本文结合开源的Linux系统,通过在其上引入窗口约束描述的QoS机制,采用合适的调度机制来满足弱硬实时系统的需求,与此同时开展了以下的研究:
1)在研究基于窗口约束(m,k)模型的实时系统的基础上,给出了一种组合窗口约束(m,k)∧＜(?),k＞的实时系统,并针对其给出了一种新的组合窗口约束的调度算法,该算法充分利用组合约束的特点,考虑本次调度对该窗口的可调度的影响来确定任务的优先级,并以此来提高任务的可调度性、减少组合窗口限制违例。仿真试验表明该算法在组合窗口约束的调度上,优于传统的独立比较两个约束确定优先级的调度算法;
2)结合组合窗口约束描述任务QoS更准确和便于调度算法设计的优点,同时针对标准Linux内核只提供三种调度策略:SCHED__RR、SCHED__FIFO、SCHED__OTHER,它们是无法实现具有QoS要求的任务调度的缺陷。本文通过可加载模块的方法,修改schedule()的调度策略,给出了组合窗口约束调度在Linux内核上的具体实现框架。
The real-time system has characters such as response in time, high dependability, dedication and less artificial interference, it was used initially applied to the field of military and industrial control. However, with the rapid development of computer and internet technology, real-time technology has been applied more and more to soft real-time system (SRTS), such as real-time network transmission, video transmission and multimedia processing. This SRTS is different from hard real-time systems that mandatory limit the deadline of jobs, and different from some soft real-time systems that don't make exactly rules for jobs. These new applications have a certain quality of service (QoS) requirements, which need satisfy the deadlines and loss-tolerance for jobs. As a result of these new features, Traditional static real-time systems and common operation system that based on fair scheduling can't satisfy these new applications. At the same time, window theory of constraints have incomparable advantages than probability constraints in describing QoS, it receives the majority of scholars research andextensive attention in recent years.
Based on the above background, this dissertation imports a QoS mechanism which described by window constraints into Linux kernel and uses a suitable scheduler for satisfying weakly hard real-time systems demands. And then contents about this were studied:
1) Based on the research of window-constrained real-time system with (m,k) constraints, a non-overlapping assembled window-constrained real-time system with (m, k)(?)
2) Combining the advantages of assembled window-constraints in exactly describing Qos and designing scheduler. And for the bugs of standard Linux kernel only can supply three schedulers: SCHED_RR, SCHED_FIFOandSCHED_OTHER, which can't satisfy tasks' QoS. By using the method of lodable kernel model (LKM), this dissertation revised schedule()'s strategy, and give a concrete realization of the framework for AWCS in Linux kernel.
引文
[1] R.-T.Sheu, J.-L.C.Wu. Performance Analysis of Rate Control with Scaling Qos Parameters for Multimedia Transmissions. In 1EE Proc. of Commun. TCChuah. 2003. 361 366
[2] C Buttazzo Giorgio. Hard Real-lime Computing Systems: Predictable Schedulings Algorithms and aplications. Kluwer Academic Publishers, 1997
[3] Real Time News Group FAQ. Real-Time Definition. URL: http://www. realtimeinfo.be/encyc/publications/faq/rtfaq.htm. 2002
[4] John A. Stankovic and Krithi Ramamritham.Hard Real-Time Systems, volume 819 of IEEE Tutorials.IEEE, 1988.
[5] S. Madden, M. J. Franklin, J. M. Hellerstein, and W. Hong.TAG: A tiny aggregation service for ad-hoc sensor networks. In Proceedings of Operating Systems Design and Implementation.USENIX, December 2002.
[6] G.Bernat, A.Burns. Specification and Analysis of Weakly Hard Real-Time Systems. PhD thesis. Department de Ciencies Matematiques Informatica, Universitat de les Illes Balears, Spain, 1998.
[7] M. Hamdaoui and P. Ramanathan. A dynamic priority assignment technique for streams with (m,k)-firm deadlines.IEEE Transactions on Computers, April 1995.
[8] C. L. Liu and J. W. Layland, "Scheduling algorithms for multiprogramming in a hard real time environment," J. ACM, vol. 20, no. 1,pp. 46-61, 1973.
[9] Lehoczky,J.P.,L .Sha,andJ .K.Strosinder,En hanceda periodic responsiveness inhard real-time environments[C].Proceedings of IEEE Real-Time Systems Symposium, Washington:IEEE Computer Society Press, 1987:261-27.
[10] Neil Audsley and Alan Burns. Deadline-monotonic scheduling[R]. Technical Report YCS146,York:Department of Computer Science,University of York, 1990 .
[11] Lui Sha, Ragunathan Rajkumar, John P .Lehockzy. Priority Inheritance Protocols: An Approach to Real-Time Synchronization IEEE TRANSACTIONS ON COMPUTERS, VOL. 39, NO. 9, SEPTEMBER 1990.
[12] Richard West and Karsten Schwan, "Dynamic Window-Constrained Scheduling for Multimedia Applications" , in Proceedings of the IEEE International Conference on Multimedia Computing and Systems (ICMCS), 1999.
[13] Richard West, Karsten Schwan and Christian Poellabauer, "Scalable Scheduling Support for Loss and Delay Constrained Media Streams", in Proceedings of the 5th IEEE Real-Time Technology and Applications Symposium(RTAS),1999.
[14]Richard West and Christian Poellabauer,"Analysis of a Window-Constrained Scheduler for Real-Time and Best-Effort Packet Streams",in Proceedings of the 21st IEEE Real-Time Systems Symposium(RTSS),2000.
[15]Richard West,Ivan Ganev and Karsten Schwan,"Window-Constrained Process Scheduling for Linux Systems",in Proceedings of the 3rd Real-Time Linux Workshop,Milan,Italy,November 2001.
[16]Richard West,Yuting Zhang,Karsten Schwan and Christian Poellabauer,"Dynamic Window-Constrained Scheduling of Real-Time Streams in Media Servers",IEEE Transactions on Computers,Volume 53,Number 6,pp.744-759,June 2004.
[17]Yuting Zhang,Richard West and Xin Qi,"A Virtual Deadline Scheduler for Window-Constrained Service Guarantees",Technical Report,2004-013,Boston University,March 2004.
[18]Yuting Zhang and Richard West,"End-to-end Window-Constrained Scheduling for Real-Time Communication",in Proceedings of the 10th International Conference on Real-Time and Embedded Computing Systems and Applications(RTCSA'04),August 2004.
[19]Yuting Zhang,Richard West and Xin Qi,"A Virtual Deadline Scheduler for Window-Constrained Service Guarantees",in Proceedings of the 25th IEEE Real-Time Systems Symposium(RTSS),December 2004.
[20]邹勇,李明树,王青.开放式实时系统的调度理论与方法分析.软件学报,2003,14(1):83-90。
[21]涂刚,阳富民,卢炎生。基于反馈算法的灵活实时调度器的设计与实现。计算机工程与科学,2005年第27卷第27期:50-52。
[22]邹勇,李明树.开放式实时环境中的集成调度框架.计算机研究与发展。
[23]基于模型的窗口限制实时系统的分析与研究.计算机研究与发展.42(8):1445-1451,2005。
[24]Jiming Chen,Zhi Wang,Yeqiong Song,You xian S un.Scalability and QoS Guarantee f or Streams with(m,k)-Firm Deadline.Journal of Computer Standards and Interfaces.2005.
[25]陈积明,DWCS和DBF的动态性能比较、Technicalre port,浙江大学现代控制工程研究所,2003。
[26]尹红霞,王智,孙优贤.一种基于(m,k)-firm的加权公平队列调度算法.浙江大学学报工学版,2005.第39卷第10期。
[27]Z.Deng J.W.-S.Liu J.Sun A scheme for scheduling hard-real-time applicationsin open environment[C].In:Proceedings of the 9th Euromicro Workshop on Real-Time Systems.Los Alamitos,CA:IEEE Computer Society Press,1997:155- 185.
[28]M Spuriand G Butazzo.Scheduling Aperiodic Tasks in Dynamic Priority Systems[J].Real-Time Systems,1996,10(2):179-210.
[29]Luca Abeniand Giorgio Buttazzo.Integrating multimedia applications in hard real-time systems[C].In Proceedings of the IEEE Real-Time Systems Symposim,Madrid,Spain:IEEE Computer Society Press- December 1998.
[30]徐翔.IP网络下QoS体系结构分析.中国科技信息.2005,15(3):50-54。
[31]Bennet J,Zhang H.WF2Q:Worst-case Fair Weighted Fair Queueing[C].IEEE INFOCOM'96,San Francisco,CA:IEEE.1996.120-128.
[32]Parekh Ak.A generalized processor sharing approach to flow control in integrated services networks[D].Boston:Massachusetts Institute of Technology,1992.
[33]J.Lehoczky,L.Sha,Y.Ding.The rate monotonic scheduling algorithm:exact characterization and average case behavior.In Real Time SystemsSymposium.Santa Monica,California,USA.1989.166 171.
[35]何军,孙玉方.提高软非周期任务相应性能的调度算法.软件学报,1998,9(10):721 727。
[36]G.C.Buttazzo,F.Sensini.Optimal Deadline Assignment for Scheduling Soft Aperiodic Tasks in Hard Real-Time Environments.IEEE Transactions on Computers,1999.10,48(10):1035 1052.
[37]Lehoczky,J.P,Fixed Priority Scheduling of Periodic Task Setswith Arbitrary Deadlines.Proceedings of the IEEE Real-Time Systems Symposium,Dee,1990.
[38]Sprunt,H.M.B.,Sha,L.,and Lehoczky,J.P.Aperiodic TaskScheduling on Hard Real-TimeS ystems.The Real-Time Systems Journal,June,1989.
[39]杨善林,凌骥生,褚伟等.“铸铁材质参数液态在线智能检测系统”技术报告.合肥工业大学网络所。
[40]涂刚.软实时系统任务调度算法研究[博士论文],武汉:华中科技大学,(57-58)2004。
[41]A.K.Mok and W.Wang.Window-constrained real-time periodic task scheduling.In Proceedings of the 22st IEEE Real-Time Systems Symposium,2001.
[42]朱响斌,涂时亮.Linux的实时性能测试,微电子学与计算机。21(11), 2004:85-88。
[43]厉海燕,李新明.Linux抢占式内核的研究与实现,计算机工程于设计。2005年9月第26卷(2395-2399)。
[44]余兵,黎忠文.Linux操作系统实时性分析,计算机技术与发展。第17卷第9期2007年9月(41-47)。
[45]Morgan K.A Response to Real Time and Linux,Part 3[M].Santa Clara:Montavista Software Inc,2002.
[46]吴一民.Linux实时化研究[J].计算机应用与软件,2003(1):9-10。
[47]M.Barabanov and V Yodaiken.Introducing Real-Time Linux[J].Linux Journal,34(2),F ebruary 1997.
[48]Andy Bavier,Thiemo Voigt,Mike Wawrzoniak,Larry Peterson,SILK:Scout Paths in the Linux Kernel,Technical Report,Nov 2001.
[49]Goyal and X.Guo and H.M.Vin,A Hierarchical CPU Scheduler for Multimedia Operating Systems,Proceedings of 2nd Symposium on Operating System Design and Implementation(OSDI'96),Seattle,WA,pages 107-122,October 1996.
[50]M.Barabanov and V Yodaiken.Introducing Real-Time Linux[J].Linux Journal,34(2),February 1997.
[51]须文波,张星烨,欧爱辉.实时RTAI2Linux操作系统的分析与研究.苏州大学学报(自然科学版)第19卷13期。
[52]Srinivasan B.A firm real-time system implementation using commercial off-the shelf hardware and free software:(master thesis).American:University of Kansas,1998.
[53]http://www.ibm.com/de veloperworks/cn/linux/embed/1-realtime/index.html
[54]毛德操,胡希明.Linux内核源代码情景分析[M].杭州:浙江大学出版社,2001。
[55]朱响斌。开放式实时Linux的研究与设计[博士学位论文]上海:复旦大学,2005。
[56]马溪骏,邹道生,褚伟.组合窗口约束(m,k)~∧＜(?),k＞的实时系统分析与研究[J].小型微型计算机系统杂志,已录用。
[2] C Buttazzo Giorgio. Hard Real-lime Computing Systems: Predictable Schedulings Algorithms and aplications. Kluwer Academic Publishers, 1997
[3] Real Time News Group FAQ. Real-Time Definition. URL: http://www. realtimeinfo.be/encyc/publications/faq/rtfaq.htm. 2002
[4] John A. Stankovic and Krithi Ramamritham.Hard Real-Time Systems, volume 819 of IEEE Tutorials.IEEE, 1988.
[5] S. Madden, M. J. Franklin, J. M. Hellerstein, and W. Hong.TAG: A tiny aggregation service for ad-hoc sensor networks. In Proceedings of Operating Systems Design and Implementation.USENIX, December 2002.
[6] G.Bernat, A.Burns. Specification and Analysis of Weakly Hard Real-Time Systems. PhD thesis. Department de Ciencies Matematiques Informatica, Universitat de les Illes Balears, Spain, 1998.
[7] M. Hamdaoui and P. Ramanathan. A dynamic priority assignment technique for streams with (m,k)-firm deadlines.IEEE Transactions on Computers, April 1995.
[8] C. L. Liu and J. W. Layland, "Scheduling algorithms for multiprogramming in a hard real time environment," J. ACM, vol. 20, no. 1,pp. 46-61, 1973.
[9] Lehoczky,J.P.,L .Sha,andJ .K.Strosinder,En hanceda periodic responsiveness inhard real-time environments[C].Proceedings of IEEE Real-Time Systems Symposium, Washington:IEEE Computer Society Press, 1987:261-27.
[10] Neil Audsley and Alan Burns. Deadline-monotonic scheduling[R]. Technical Report YCS146,York:Department of Computer Science,University of York, 1990 .
[11] Lui Sha, Ragunathan Rajkumar, John P .Lehockzy. Priority Inheritance Protocols: An Approach to Real-Time Synchronization IEEE TRANSACTIONS ON COMPUTERS, VOL. 39, NO. 9, SEPTEMBER 1990.
[12] Richard West and Karsten Schwan, "Dynamic Window-Constrained Scheduling for Multimedia Applications" , in Proceedings of the IEEE International Conference on Multimedia Computing and Systems (ICMCS), 1999.
[13] Richard West, Karsten Schwan and Christian Poellabauer, "Scalable Scheduling Support for Loss and Delay Constrained Media Streams", in Proceedings of the 5th IEEE Real-Time Technology and Applications Symposium(RTAS),1999.
[14]Richard West and Christian Poellabauer,"Analysis of a Window-Constrained Scheduler for Real-Time and Best-Effort Packet Streams",in Proceedings of the 21st IEEE Real-Time Systems Symposium(RTSS),2000.
[15]Richard West,Ivan Ganev and Karsten Schwan,"Window-Constrained Process Scheduling for Linux Systems",in Proceedings of the 3rd Real-Time Linux Workshop,Milan,Italy,November 2001.
[16]Richard West,Yuting Zhang,Karsten Schwan and Christian Poellabauer,"Dynamic Window-Constrained Scheduling of Real-Time Streams in Media Servers",IEEE Transactions on Computers,Volume 53,Number 6,pp.744-759,June 2004.
[17]Yuting Zhang,Richard West and Xin Qi,"A Virtual Deadline Scheduler for Window-Constrained Service Guarantees",Technical Report,2004-013,Boston University,March 2004.
[18]Yuting Zhang and Richard West,"End-to-end Window-Constrained Scheduling for Real-Time Communication",in Proceedings of the 10th International Conference on Real-Time and Embedded Computing Systems and Applications(RTCSA'04),August 2004.
[19]Yuting Zhang,Richard West and Xin Qi,"A Virtual Deadline Scheduler for Window-Constrained Service Guarantees",in Proceedings of the 25th IEEE Real-Time Systems Symposium(RTSS),December 2004.
[20]邹勇,李明树,王青.开放式实时系统的调度理论与方法分析.软件学报,2003,14(1):83-90。
[21]涂刚,阳富民,卢炎生。基于反馈算法的灵活实时调度器的设计与实现。计算机工程与科学,2005年第27卷第27期:50-52。
[22]邹勇,李明树.开放式实时环境中的集成调度框架.计算机研究与发展。
[23]基于
[24]Jiming Chen,Zhi Wang,Yeqiong Song,You xian S un.Scalability and QoS Guarantee f or Streams with(m,k)-Firm Deadline.Journal of Computer Standards and Interfaces.2005.
[25]陈积明,DWCS和DBF的动态性能比较、Technicalre port,浙江大学现代控制工程研究所,2003。
[26]尹红霞,王智,孙优贤.一种基于(m,k)-firm的加权公平队列调度算法.浙江大学学报工学版,2005.第39卷第10期。
[27]Z.Deng J.W.-S.Liu J.Sun A scheme for scheduling hard-real-time applicationsin open environment[C].In:Proceedings of the 9th Euromicro Workshop on Real-Time Systems.Los Alamitos,CA:IEEE Computer Society Press,1997:155- 185.
[28]M Spuriand G Butazzo.Scheduling Aperiodic Tasks in Dynamic Priority Systems[J].Real-Time Systems,1996,10(2):179-210.
[29]Luca Abeniand Giorgio Buttazzo.Integrating multimedia applications in hard real-time systems[C].In Proceedings of the IEEE Real-Time Systems Symposim,Madrid,Spain:IEEE Computer Society Press- December 1998.
[30]徐翔.IP网络下QoS体系结构分析.中国科技信息.2005,15(3):50-54。
[31]Bennet J,Zhang H.WF2Q:Worst-case Fair Weighted Fair Queueing[C].IEEE INFOCOM'96,San Francisco,CA:IEEE.1996.120-128.
[32]Parekh Ak.A generalized processor sharing approach to flow control in integrated services networks[D].Boston:Massachusetts Institute of Technology,1992.
[33]J.Lehoczky,L.Sha,Y.Ding.The rate monotonic scheduling algorithm:exact characterization and average case behavior.In Real Time SystemsSymposium.Santa Monica,California,USA.1989.166 171.
[35]何军,孙玉方.提高软非周期任务相应性能的调度算法.软件学报,1998,9(10):721 727。
[36]G.C.Buttazzo,F.Sensini.Optimal Deadline Assignment for Scheduling Soft Aperiodic Tasks in Hard Real-Time Environments.IEEE Transactions on Computers,1999.10,48(10):1035 1052.
[37]Lehoczky,J.P,Fixed Priority Scheduling of Periodic Task Setswith Arbitrary Deadlines.Proceedings of the IEEE Real-Time Systems Symposium,Dee,1990.
[38]Sprunt,H.M.B.,Sha,L.,and Lehoczky,J.P.Aperiodic TaskScheduling on Hard Real-TimeS ystems.The Real-Time Systems Journal,June,1989.
[39]杨善林,凌骥生,褚伟等.“铸铁材质参数液态在线智能检测系统”技术报告.合肥工业大学网络所。
[40]涂刚.软实时系统任务调度算法研究[博士论文],武汉:华中科技大学,(57-58)2004。
[41]A.K.Mok and W.Wang.Window-constrained real-time periodic task scheduling.In Proceedings of the 22st IEEE Real-Time Systems Symposium,2001.
[42]朱响斌,涂时亮.Linux的实时性能测试,微电子学与计算机。21(11), 2004:85-88。
[43]厉海燕,李新明.Linux抢占式内核的研究与实现,计算机工程于设计。2005年9月第26卷(2395-2399)。
[44]余兵,黎忠文.Linux操作系统实时性分析,计算机技术与发展。第17卷第9期2007年9月(41-47)。
[45]Morgan K.A Response to Real Time and Linux,Part 3[M].Santa Clara:Montavista Software Inc,2002.
[46]吴一民.Linux实时化研究[J].计算机应用与软件,2003(1):9-10。
[47]M.Barabanov and V Yodaiken.Introducing Real-Time Linux[J].Linux Journal,34(2),F ebruary 1997.
[48]Andy Bavier,Thiemo Voigt,Mike Wawrzoniak,Larry Peterson,SILK:Scout Paths in the Linux Kernel,Technical Report,Nov 2001.
[49]Goyal and X.Guo and H.M.Vin,A Hierarchical CPU Scheduler for Multimedia Operating Systems,Proceedings of 2nd Symposium on Operating System Design and Implementation(OSDI'96),Seattle,WA,pages 107-122,October 1996.
[50]M.Barabanov and V Yodaiken.Introducing Real-Time Linux[J].Linux Journal,34(2),February 1997.
[51]须文波,张星烨,欧爱辉.实时RTAI2Linux操作系统的分析与研究.苏州大学学报(自然科学版)第19卷13期。
[52]Srinivasan B.A firm real-time system implementation using commercial off-the shelf hardware and free software:(master thesis).American:University of Kansas,1998.
[53]http://www.ibm.com/de veloperworks/cn/linux/embed/1-realtime/index.html
[54]毛德操,胡希明.Linux内核源代码情景分析[M].杭州:浙江大学出版社,2001。
[55]朱响斌。开放式实时Linux的研究与设计[博士学位论文]上海:复旦大学,2005。
[56]马溪骏,邹道生,褚伟.组合窗口约束(m,k)~∧＜(?),k＞的实时系统分析与研究[J].小型微型计算机系统杂志,已录用。