JNTU
JNTU MCA OPERATING SYSTEMS Previous Question Paper (October/ November - 2020 - R15)
Answer any five questions. All questions carry equal marks.
Main
What is an operating system? Discuss the goals and functions of an operating system.
Answer
An operating system is a system software that acts as an intermediary between the computer hardware and the user, managing hardware resources and providing a platform for application programs to execute.
The primary goals of an operating system are:
- Convenience: Making the computer system easier and more efficient to use.
- Efficiency: Allowing the computer system resources to be used in an efficient manner.
- Evolution: Designed to permit effective development, testing, and introduction of new system functions without interfering with service.
The core functions include:
- Process Management: Creating, scheduling, and terminating processes, and managing inter-process communication.
- Memory Management: Tracking memory usage, allocating and deallocating memory space for processes.
- File Management: Managing file creation, deletion, directory structures, and file access permissions.
- I/O Management: Managing device drivers and buffering, caching, and spooling for hardware devices.
- Security and Protection: Ensuring controlled access to system resources and protecting data from unauthorized users.
Distinguish between client-server and peer-to-peer models of a distributed system.
Answer
| Feature | Client-Server Model | Peer-to-Peer Model |
|---|---|---|
| Architecture | Centralized; clients request services from a dedicated server. | Decentralized; all nodes act as both clients and servers. |
| Resource Control | Server maintains control over shared resources. | Resources are distributed across all participating nodes. |
| Scalability | Limited by server capacity; adding clients increases server load. | Highly scalable; adding nodes increases total system capacity. |
| Reliability | Single point of failure at the server. | High fault tolerance; no single point of failure. |
| Complexity | Easier to manage and secure due to centralization. | Complex to manage, secure, and maintain consistency. |
How does a micro kernel differ from a monolithic kernel? Explain the advantages and disadvantages of system calls over library functions.
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What is the difference between a process, a program and a thread?
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Explain SJF and SRTF Scheduling algorithms with an illustrative example.
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Compare preemptive and non-preemptive scheduling methods.
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Describe how semaphore can be used for block wake up synchronization between processes.
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How many page faults occur for the following reference string with three and four page frames using FIFO, LRU and OPTIMAL page replacements algorithms? Assume that initially frames are empty.
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Explain about the structure of page table.
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Explain about virtual memory.
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Suppose the head of a moving-head disk with 200 tracks, numbered 0 to 199, is currently serving a request at track 143 and has just finished a request at track 25. If the queue of requests is kept in FIFO order: 86, 147, 91, 177, 94, 150, 102, 175, 130. What is the total head movement to satisfy these requests for the following disk scheduling algorithms: FIFO, SSTF, SCAN, LOOK.
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Consider a system with five processes P0 through P4 and three resource types A, B, C. Resource type A has 10 instances, resource type B has 5 instances, and resource type C has 7 instances. Suppose that, at time T0, the following snapshot of the system has been taken:
| Processes | Allocation (A B C) | Max (A B C) | Available (A B C) |
|---|---|---|---|
| P0 | 0 1 0 | 7 5 3 | 3 3 2 |
| P1 | 2 0 0 | 3 2 2 | |
| P2 | 3 0 2 | 9 0 2 | |
| P3 | 2 1 1 | 2 2 2 | |
| P4 | 0 0 2 | 4 3 3 |
What is the content of the matrix Need?
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Is the system in a safe state?
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