My interest in NT is primarily as a vehicle for investigating issues of support for real-time computing in desktop operating systems. The motivation for real-time services comes from the desire to support a variety of continuous-media applications ranging from interactive, high bandwidth audio/video applications to distributed, immersive virtual environments.

My research of late has considered the use of proportional share research allocation to integrate real-time and non-real-time scheduling. In a proportional share system, processes are assigned a weight which determines a share (percentage) of the resource they are to receive. The resource is then allocated in discrete-sized time quanta in such a manner that each process makes progress at a precise, uniform rate. Proportional share allocation algorithms are of interest because (1) they provide a natural means of seamlessly integrating real- and non-real-time processing requirements in a general purpose operating system, (2) they are easy to implement (and in particular, easier than more traditional forms of real-time support such as periodic tasks), (3) they provide a simple and effective means of precisely controlling the real-time performance of a process including uniform, predictable degradation in times of system overload, and (4) they provide a natural mean of policing processes so that process that use more of a resource than they request have no ill-effect on well-behaved processes.

Previously we have implemented a specific form of proportional share cpu scheduling in FreeBSD [1,2]. We are now interested in extending this work to consider Windows operating systems such as NT.

[1] On the Duality between Resource Reservation and Proportional Share Resource Allocation, I. Stoica, H. Abdel-Wahab, K. Jeffay, in Proc. SPIE/ACM Multimedia Computing and Networking 1997, SPIE Proceedings Series, Volume 3020, San Jose, CA, February 1997, pages 207-214. (https://www.cs.unc.edu/Research/dirt/abstracts/MMCN-97-abs.html)

[2] A Proportional Share Resource Allocation Algorithm For Real-Time, Time-Shared Systems, I. Stoica, H. Abdel-Wahab, K. Jeffay, S.K. Baruah, J.E. Gehrke, and C.G. Plaxton, Proceedings of the 17th IEEE Real-Time Systems Symposium, Washington, DC, December 1996, pages 288-299. (https://www.cs.unc.edu/Research/dirt/abstracts/RTSS-96a-abs.html)

Kevin Jeffay
Department of Computer Science
University of North Carolina
Chapel Hill, NC 27599-3175
jeffay@cs.unc.edu
https://www.cs.unc.edu/~jeffay

(919) 962-1938
(919) 962-1799 (FAX)