Preemptive Scheduling and Mutex

Goal

• Understand how to use interrupt disable and atomic read-modify-write to implement mutual exclusion.

Reading Assignments

• MOS 2.3.3-2.3.4

Discussion topics

• The simplest way to implement Acquire() and Release() is:

   Release()
   {
        enable interrupts;
   }

Do you think it works?  If you think it works, say under what condition it works.  If do not think so, explain why it does not work and how would you make it work.
 
• The textbook mentioned about using test-and-set instruction to implement mutual exclusion.  How would you use it to implement Acquire() and Release()?