Question:

(a) Modern processors operate in one of two modes: one for the operating system and one for applications. What is the purpose of having these two modes?

What are the usual mechanisms for switching from system mode to application mode, and vice versa?

(b) (i) Compare UMA (Uniform Memory Access) and NUMA (Non Uniform Memory Access) Microprocessor System.

(ii) What is the cache coherency problem in a multiprocessor environment?

(c) Discuss the following multiprocessor scheduling strategies Space Sharing Gang Scheduling.

(d) Three source files normally take 10 seconds, 18 seconds and 30 seconds respectively to compile by themselves on one processor in a processor pool. How long should it take to compile all the files using two processors? Explain what is liable to limit the time attainable for a parallel compilation, especially as the number of compilations increases.

(e) Steaming audio or video services are usually implemented over UDP instead of TCP. Assuming that both impose roughly the same computational burden on the processor, explain why this is the case?