Any data exchanged between the processor and main memory uses the memory bus, sharing it with data exchanged between I/O devices and main memory. If the processor and a device try to transfer data at the same time, an impact can be seen on the processor as well as on the device. As a result, the execution time of an application on the processor may increase due to memory-bus load generated by I/O devices. In real-time environments, this impact can result in missed deadlines and a behavior that is different to that intended by the designer of the system. This paper gives a method for describing and quantifying the impact of such load on applications executed by the processor.

We present a unified model for admission and scheduling, applicable for various active resources such as CPU or disk to assure a requested quality in situations of temporary overload. The model allows us to predict and control the behavior of applications based on given quality requirements. It uses the variations in the execution time, i.e., the time any active resource is needed We split resource requirements into a mandatory part which must be available and an optional part which should be available as often as possible but at least with a certain percentage. In combination with a given distribution for the execution time we can move away from worst-case reservations and drastically reduce the amount of reserved resources for applications which can tolerate occasional deadline misses. This increases the number of admittable applications. For example, with negligible loss of quality our system can admit more than two times the disk bandwidth than a system based on the worst-case. Finally, we validated the predictions of our model by measurements using a prototype real-time system and observed a high accuracy between predicted and measured values.

article The performance of μ-kernel-based systems Share on Authors: Hermann Härtig Dresden University of Technology, Department of Computer Science, D-01062 Dresden, Germany Dresden University of Technology, Department of Computer Science, D-01062 Dresden, GermanyView Profile , Michael Hohmuth Dresden University of Technology, Department of Computer Science, D-01062 Dresden, Germany Dresden University of Technology, Department of Computer Science, D-01062 Dresden, GermanyView Profile , Jochen Liedtke IBM T. J. Watson Research Center, 30 Saw Mill River Road, Hawthorne, NY IBM T. J. Watson Research Center, 30 Saw Mill River Road, Hawthorne, NYView Profile , Sebastian Schönberg Dresden University of Technology, Department of Computer Science, D-01062 Dresden, Germany Dresden University of Technology, Department of Computer Science, D-01062 Dresden, GermanyView Profile , Jean Wolter Dresden University of Technology, Department of Computer Science, D-01062 Dresden, Germany Dresden University of Technology, Department of Computer Science, D-01062 Dresden, GermanyView Profile Authors Info & Claims ACM SIGOPS Operating Systems ReviewVolume 31Issue 5Dec. 1997 pp 66–77https://doi.org/10.1145/269005.266660Online:01 October 1997Publication History 177citation6,894DownloadsMetricsTotal Citations177Total Downloads6,894Last 12 Months272Last 6 weeks40 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access