Question

9. What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?

Answer 1

Answer:

First of all we will see what is thrashing. From "Thrashing" we means that it is a condition in a virtual storage system in which excessive paging operations takes place. This causes the performance of the computer to degrade or collapse.

Since we have seen the concept of thrashing now we will see what causes thrashing. The causes of thrashing are:

1. When we CPU utilization is too low and the level of multiprogramming is kept on increasing by the user then the performance of CPU degrades.

2. Thrashing is also caused by allocation of minimum number of pages required by a process forcing it to continuously page fault.

The thrashing can be detected by system by evaluating the level of CPU utilization as compared to the level of multiprogramming.

There are various ways through which we can prevent thrashing.They are:

1. The working set strategy model: This defines how many frames a process is actually using.

2. Locality Model: When a process executes it moves from locality to locality.

3. By decreasing the level of multiprogramming the problem of thrashing can be decreased.