In the previous article, I have explained the important topics from DBMS for GATE. This blog is on how to prepare Operating System for GATE and for job interviews.
If you look at the GATE syllabus, Operating System is core subject. Every year GATE asks around 8-10 marks of question from this subject.
So, consider this as an important subject. Below are some important topics, notes and tricks that you have to follow to score good marks with minimum efforts.
In this blog, first I will list some important topics to focus on. And later, we will discuss important OS questions and answers in detail.
Important Topics on Operating System (OS)
Now, let’s discuss some important topics in detail with shortcuts one-by-one..
If you are preparing for GATE, check the GATE exam details and dates.
Table of Contents
From this topic, they ask standard questions every year. One question can be expected from multiprogramming and multitasking operating systems. The rest of them are not so important.
Real Time Example:
Consider in a class, there are five students and each student has five questions with them. As a teacher, I have two cases.
At above, the first case is of Multiprogramming and 2nd case is of multitasking. (consider teacher as CPU and student as a process)
Here, they ask questions on the Fork system call mainly. Practice questions on Kernel operating mode, user operating mode, and fork system call.
Some Important Points to Solve Questions related to System Call
2^n-1, where n is the number of fork system call. There can be questions where you have to find the number of child processes requires for the execution of a given recursive program.
Learn the difference between process and thread in OS.
This topic is quite important from a GATE point of view, they ask frequent ques from Round Robin, SRTF, and priority-based algorithms. The questions will be like Arrival time, Burst time will be given, you need to calculate different parameter.
CPU Scheduling Formulas:
Here are some of the basic formulas you need to solve CPU scheduling problems.
Turnaround Time = Completion Time - Arrival Time
Waiting time = Turnaround Time - Burst time
Response Time = Time in which process got CPU for First Time - Arrival Time
Short Tricks and Points to Solve CPU Scheduling Questions:
GATE ask a bit complicated topic from this topic, only practice will make you perfect here. Practice as many questions as you can on Binary Semaphore.
Few Tips to Remember while Solving Semaphore Questions:
From this topic, they ask about first, best and worse fit algorithms.
Like some partition blocks of different sizes will be given and some processes of different sizes. You have to arrange them according to the algorithm.
Few Points to Remember while Solving Questions on Fragmentation:
What is the difference between First, Best and Worst Fit Algorithm?
In the DYNAMIC PARTITIONING, the worst-fit algorithm works best. And in static partitioning best-fit algorithm works best.
Many of the times, GATE asks questions of page hit and fault calculation algorithm.
You need to check carefully whether it’s hit or fault.
What is Page Hit?
If the process number which is demanded by the CPU is present then it’s a hit otherwise fault.
What is difference between FIFO, LRU and Optimal Algorithm?
Number of frames will be given in the question itself.
Next topic you should consider to prepare Operating System for GATE is Disc Scheduling.
Here, GATE mainly focuses on the SCAN and LOOK algorithm. Just practice some basic numerical on that and have a clear concept on DISC structure.
What is the difference between SCAN and LOOK algorithm?
Just practice some numerical on how to calculate the average time and have a clear understanding of all the disc scheduling algorithm.
Important Questions from Disc Scheduling Algorithm and Paging:
This topic is quite important for GATE as well as interview also. GATE will surely ask you a question on BANKER’S ALGORITHM. So, practice at least 4-5 difficult problems in that.
Question will be like– they will give you currently allocated resource and the max need, and a total number of resources present. You need to check the system is stable or not, the sequence of processes, the deadlock will occur or not, etc.
Few Points to Keep in Mind while Solving Numerical:
Banker’s Algorithm is a part of deadlock voidance.
JUST FOCUS ON THESE POINTS NOW, AND YOU WILL GET GOOD MARKS IN THE SUBJECT.
Hope this helps you to prepare Operating System for GATE or job interview. If you have any doubt, ask me in the comment. All the best!