Operating System, processes and threads

1.

Briefly describe the information that the O.S. must maintain for

each process. Describe what is done in a context switch.

2.

Briefly describe the difference between process and threads.

Which is more expensive to context switch and why?

3.

Threads can be handled in user mode or kernel mode. Describe

the advantages and disadvantages of each.

4.

Describe a situation in which several threads are running and

require the use of a semaphore or mutex. In other words what is a

critical region and why is it necessary.

5.

Why is an atomic instruction like testAndSet needed to implement

a mutex. What is the problem with busy waiting, and when would

it be ok to use. What is the alternative to busy waiting?