CS 481: Assignment #1

Assume you have a dial that allows you to set the length of the time slice in a simple, time-shared operating system. Further assume that processes in the runnable queue are handled on a first-come, first-served basis.

Describe as accurately as possible what you would observe as you used the dial to try possible settings of the slice length, from a minimum of one CPU cycle to a maximum of infinity. Points of interest along the way might include (in no particular order): (i) the context-switching time for an interrupt (saving and restoring registers); (ii) the average CPU burst (continuous use of the CPU without resource request or release) of a process; (iii) the average time between external interrupts; (iv) the average time from resource request to resource acquisition.

Where would you set your dial if your system was to run a small number of large, CPU-intensive jobs? if it was to serve a large student population? if it was to be used in air-traffic control? Discuss each choice (why did you make the choice? is the result any good or would you have to modify other mechanisms? etc.).