Solutions for Critical Section Problem

Summary of Techniques for Critical Section Problem

Software

1. Peterson's Algorithm: based on busy waiting
2. Semaphores: general facility provided by operating system (e.g., OS/2)
• based on low-level techniques such as busy waiting or hardware assistance
• described in more detail below
3. Monitors: programming language technique.

Hardware

1. Exclusive access to memory location
• always assumed
2. Interrupts that can be turned off
• must have only one processor for mutual exclusion
3. Test-and-Set: special machine-level instruction
4. Swap: atomically swaps contents of two words