Q39.Marks: +2.0UGC NET Paper 2: Computer Science 2nd January 2026 Shift 1
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Thrashing occurs when a process spends more time on paging than executing. Reason R: It happens when the degree of multiprogramming is too low and frames are insufficient.
In the light of the above statements, choose the most appropriate answer from the options given below
1.Both A and R are correct and R is the correct explanation of A
2.Both A and R are correct but R is NOT the correct explanation of A
3.A is correct but R is not correct✓ Correct
4.A is not correct but R is correct
Solution
The correct answer is A is correct but R is not correct.
Key Points
Thrashing is a situation that occurs in an operating system when a process spends more time on paging (swapping pages in and out of memory) than executing its actual tasks.
It is typically caused by insufficient memory allocation or an excessive degree of multiprogramming, leading to frequent page faults and reduced system performance.
The assertion (A) is correct because thrashing indeed refers to the condition where a process spends more time on paging than execution.
The reason (R) is incorrect because thrashing occurs due to a high degree of multiprogramming, not a low one, and frames being insufficient are only one contributing factor among several.
Effective memory management techniques such as working set model and page replacement algorithms can help reduce thrashing.
Additional Information
Causes of Thrashing:
Insufficient memory allocation for processes.
Excessive multiprogramming, leading to frequent page replacements.
Improper selection of page replacement algorithms.
Consequences of Thrashing:
Significant reduction in system performance due to frequent page faults.
Increased CPU overhead from managing paging operations.
Longer response times for processes and applications.
Solutions to Thrashing:
Implementing the working set model to allocate sufficient memory to active processes.
Using efficient page replacement algorithms such as Least Recently Used (LRU).
Controlling the degree of multiprogramming to maintain optimal system performance.
Important Points:
Thrashing is a critical issue in systems with limited physical memory and excessive workload.
Proper memory management policies can significantly mitigate thrashing.
Regular monitoring of system performance is essential to identify and address thrashing early.
