Problem (30 + 20 + 20 pts)

1. Solaris supports real-time (RT) processes by allowing them to occupy the priority range 100-159. Timeshare (TS) processes occupy range 0-59 and system processes run with priorities in the range 60-99. As discussed in class, the Solaris scheduler, when invoked, picks a highest ready process to run. Sketch the design of a real-time scheduler that implements EDF on top of Solaris's legacy scheduler. That is, the EDF scheduler is "virtual" in the sense that the Solaris kernel is not modified and EDF is emulated on top of Solaris's native scheduler. Discuss the accuracy and overhead of the resultant EDF-over-Solaris scheduler when compared to a kernel-level implementation of EDF.

2. Suppose you decided to implement RMS in a modern kernel aimed at supporting hard real-time MPEG video playback at a given frame rate (e.g., 30 fps). What are the main technical challenges associated with transferring the theory to practice such that hard real-time playback is guaranteed? Which of the hurdles are kernel design related and which are more application oriented? How would you go about tackling the technical challenges? Assess the "goodness" of the resultant system.

3. As a continuation of Problem 2, propose a method through which RMS scheduling for real-time video/audio may be exported to the user as a kernel service. You need to consider both the syntactic as well as semantic aspects of the proposed method.

Write your answers in a file named HW1Answers.txt (if simple text), HW1Answers.pdf, or HW1Answers.ps (if Postscript, e.g., generated from LaTeX/dvips). Please place this file in the sys/ directory and turn it in, along with the lab programming assignment.