Discuss Peterson’s solution for achieving the Mutual exclusion.
Problem: Given 2 process i and j, you need to write a program that can guarantee mutual exclusion between the two without any additional hardware support.
Solution: There can be multiple ways to solve this problem, but most of them require additional hardware support. The simplest and the most popular way to do this is by using Peterson Algorithm for mutual Exclusion.
Basically, Peterson’s algorithm provides guaranteed mutual exclusion by using only the shared memory. It uses two ideas in the algorithm,
- Willingness to acquire lock.
- Turn to acquire lock.
Explanation:
The idea is that first a thread expresses its desire to acquire lock and sets flag[self] = 1 and then gives the other thread a chance to acquire the lock. If the thread desires to acquire the lock, then, it gets the lock and then passes the chance to the 1st thread. If it does not desire to get the lock then the while loop breaks and the 1st thread gets the chance.