J. Balasubramanian, Sumant Tambe, B. Dasarathy, S. Gadgil, F. Porter, A. Gokhale, D. Schmidt
This paper provides two contributions to the study of quality of service (QoS)-enabled middleware that supports the network QoS requirements of distributed real-time and embedded (DRE) systems. First, we describe the design and implementation of NetQoPE, which is a model-driven component middleware framework that shields applications from the details of network QoS mechanisms by (1) specifying per-flow network QoS requirements, (2) performing resource allocation and validation decisions (such as admission control), and (3) enforcing per-flow network QoS at runtime. Second, we evaluate the effort required and flexibility of using NetQoPE to provide network QoS assurance to end-to-end application flows. Our results demonstrate that NetQoPE can provide network-level differentiated performance to each application flow without modifying its programming model or source code, thereby providing greater flexibility in leveraging network-layer mechanisms.
{"title":"NetQoPE: A Model-Driven Network QoS Provisioning Engine for Distributed Real-time and Embedded Systems","authors":"J. Balasubramanian, Sumant Tambe, B. Dasarathy, S. Gadgil, F. Porter, A. Gokhale, D. Schmidt","doi":"10.1109/RTAS.2008.32","DOIUrl":"https://doi.org/10.1109/RTAS.2008.32","url":null,"abstract":"This paper provides two contributions to the study of quality of service (QoS)-enabled middleware that supports the network QoS requirements of distributed real-time and embedded (DRE) systems. First, we describe the design and implementation of NetQoPE, which is a model-driven component middleware framework that shields applications from the details of network QoS mechanisms by (1) specifying per-flow network QoS requirements, (2) performing resource allocation and validation decisions (such as admission control), and (3) enforcing per-flow network QoS at runtime. Second, we evaluate the effort required and flexibility of using NetQoPE to provide network QoS assurance to end-to-end application flows. Our results demonstrate that NetQoPE can provide network-level differentiated performance to each application flow without modifying its programming model or source code, thereby providing greater flexibility in leveraging network-layer mechanisms.","PeriodicalId":130593,"journal":{"name":"2008 IEEE Real-Time and Embedded Technology and Applications Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132503788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many contemporary disk drives have built-in queues and schedulers. These features can improve I/O performance, by offloading work from the system's main processor, avoiding disk idle time, and taking advantage of vendor-specific disk characteristics. At the same time, they pose challenges for scheduling requests that have real-time requirements, since the operating system has less visibility and control over service times. While it may be possible for an operating system to obtain more predictable real-time performance by bypassing the on-disk queue and scheduler, the diversity and continuing evolution of disk drives make it difficult to extract the necessary detailed timing characteristics of a specific disk, and to generalize that approach to all hard drives. This paper demonstrates three techniques we developed in the Linux operating system to bound real-time request response times for disks with internal queues and schedulers. The first technique is to use the disk's built-in starvation prevention scheme. The second is to prevent requests from being sent to the disk when real-time requests are waiting to be served. The third is to limit the length of the on-disk queue in addition to the second technique. Our results show the ability to guarantee a wide range of desired response times while still allowing the disk to perform scheduling optimizations. These techniques can be generalized to disks from different vendors.
{"title":"Throttling On-Disk Schedulers to Meet Soft-Real-Time Requirements","authors":"M. Stanovich, T. Baker, An-I Wang","doi":"10.1109/RTAS.2008.30","DOIUrl":"https://doi.org/10.1109/RTAS.2008.30","url":null,"abstract":"Many contemporary disk drives have built-in queues and schedulers. These features can improve I/O performance, by offloading work from the system's main processor, avoiding disk idle time, and taking advantage of vendor-specific disk characteristics. At the same time, they pose challenges for scheduling requests that have real-time requirements, since the operating system has less visibility and control over service times. While it may be possible for an operating system to obtain more predictable real-time performance by bypassing the on-disk queue and scheduler, the diversity and continuing evolution of disk drives make it difficult to extract the necessary detailed timing characteristics of a specific disk, and to generalize that approach to all hard drives. This paper demonstrates three techniques we developed in the Linux operating system to bound real-time request response times for disks with internal queues and schedulers. The first technique is to use the disk's built-in starvation prevention scheme. The second is to prevent requests from being sent to the disk when real-time requests are waiting to be served. The third is to limit the length of the on-disk queue in addition to the second technique. Our results show the ability to guarantee a wide range of desired response times while still allowing the disk to perform scheduling optimizations. These techniques can be generalized to disks from different vendors.","PeriodicalId":130593,"journal":{"name":"2008 IEEE Real-Time and Embedded Technology and Applications Symposium","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121944125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianping Song, Song Han, A. Mok, Deji Chen, Mike Lucas, M. Nixon, Wally Pratt
Wireless technology has been regarded as a paradigm shifter in the process industry. The first open wireless communication standard specifically designed for process measurement and control applications, WirelessHART was officially released in September 2007 (as a part of the HART 7 Specification). WirelessHART is a secure and TDMA- based wireless mesh networking technology operating in the 2.4 GHz ISM radio band. In this paper, we give an introduction to the architecture of WirelessHART and share our first-hand experience in building a prototype for this specification. We describe several challenges we had to tackle during the implementation, such as the design of the timer, network wide synchronization, communication security, reliable mesh networking, and the central network manager. For each challenge, we provide a detailed analysis and propose our solution. Based on the prototype implementation, a simple WirelessHART network has been built for the purpose of demonstration. The demonstration network in turn validates our design. To the best of our knowledge, this is the first reported effort to build a WirelessHART protocol stack.
{"title":"WirelessHART: Applying Wireless Technology in Real-Time Industrial Process Control","authors":"Jianping Song, Song Han, A. Mok, Deji Chen, Mike Lucas, M. Nixon, Wally Pratt","doi":"10.1109/RTAS.2008.15","DOIUrl":"https://doi.org/10.1109/RTAS.2008.15","url":null,"abstract":"Wireless technology has been regarded as a paradigm shifter in the process industry. The first open wireless communication standard specifically designed for process measurement and control applications, WirelessHART was officially released in September 2007 (as a part of the HART 7 Specification). WirelessHART is a secure and TDMA- based wireless mesh networking technology operating in the 2.4 GHz ISM radio band. In this paper, we give an introduction to the architecture of WirelessHART and share our first-hand experience in building a prototype for this specification. We describe several challenges we had to tackle during the implementation, such as the design of the timer, network wide synchronization, communication security, reliable mesh networking, and the central network manager. For each challenge, we provide a detailed analysis and propose our solution. Based on the prototype implementation, a simple WirelessHART network has been built for the purpose of demonstration. The demonstration network in turn validates our design. To the best of our knowledge, this is the first reported effort to build a WirelessHART protocol stack.","PeriodicalId":130593,"journal":{"name":"2008 IEEE Real-Time and Embedded Technology and Applications Symposium","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130392404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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