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- Introduction: OS
- Booting Process
- Command Interpreter
- Dual mode of operation
- System Calls
- Difference between system call and library call
- Interrupt and Trap
- Introduction
- Scheduling Criteria, Terms and Concepts
- Different Type Scheduling Algorithms
- Longest Job First
- Longest Remaining Time First
- Highest Response Ratio Next (HRRN)
- Priority Scheduling
- Least Completed Next (LCN) Scheduling
- Multi-Level Queue Scheduling
- Multilevel Feedback Queue Scheduling
- Guaranteed Scheduling
- Fair Share Scheduling
- Lottery Scheduling
- Multi-Processor Scheduling
- Deadline Scheduling
- Rate-Monotonic Scheduling
- POSIX Real-Time Scheduling
- Priority Inversion
- Proportional Share Scheduling
- Comparison table of Scheduling Algorithm
- Algorithm Evaluation for Scheduling
- Important concept of MM
- Memory Representation as Address
- Memory layout for a Process
- Logical and Physical Address Space
- Necessity of Memory Management
- Introduction
- Concept of Non-contiguous memory allocation
- Basic concept of Paging
- Address Translation
- Process of Paging Method
- Calculation of Offset for paging
- Calculation of Logical Address Bit and number of Pages
- Calculation of Physical Address Bit and number of Frames
- Calculation of Page Table Size
- Organization of MMU
- Why Page size power of 2
- Paging Address Calculation: example1
- Paging Numeric Problem: Example2
- Paging Address Calculation: Example3
- Paging Address Calculation: Question1
- Some Important Question 2
- Paging Address Translation: Question3
- UGC NET Paging Question
- GATE Paging Question
- Number of information at Page Entry
- Exams Question on Page Entry Information
- Exam Question: Page Entry Information
- Calculates Page Table Entry Size
- Calculates Page Size
- Calculation of Optimal Page Size
- Question on Optimal Page Size
- Hashed Page Table with Example
- Inverted Page Table with Gate Question
- Question on Inverted Page Table
- Multi-Level Paging
- Multi-level paging: Example1
- Multi-level paging: Example2
- Allocation of Frames
- Subject Mock
NET and GATE question: Counting Semaphore
Q. UGC NET CS 2018 July – II
At a particular time of computation, the value of a counting semaphore is 10. Then 12 P operations and “x” V operations were performed on this semaphore. If the final value of the semaphore is 7, x will be:
(A) 8
(B) 9
(C) 10
(D) 11
Answer:
Given: counting semaphore = 10. (capacity of critical section)
12 P (Down) operations are performed. So right now capacity of critical section= 10 – 12 = -2
After that “x” V (Up) operations are performed then capacity of critical section = -2 + “x”.
Now final value of semaphore (capacity of critical section) = 7 (given)
So, -2 + x = 7
x = 7 + 2 = 9
Option: B is correct.
P and down are the same operation.
V and up are the same operation.
Q. Gate-92
A counting semaphore was initialized to 10, then 6p (wait) and 4v (signal) operations were computed on this semaphore. What is the result?
Answer:
Given: counting semaphore = 10. (capacity of the critical section).
Now 6p (wait or down) operation are completed, Then counting semaphore = 10 - 6= 4.
After 4v (signal or up) operation are completed. So, right now counting semaphore = 4 + 4 = 8
Answer: is 8.
