Operating System
OS Part-1
OS Part-2
- File Concepts and Access methods
- Free Space Management and Allocation methods
- Directory Systems and Protection
- File Organization, Sharing and Implementation issues
- Disk and Drum Scheduling
- I/O Devices Organisation & I/O Buffering
- I/O Hardware, Kernel I/O subsystem and Transforming I/O Requests to Hardware Operations
- Device Drivers and Path Management
- Device Driver Sub Modules and Procedure
- Device Scheduler and Handler
- Interrupt Service Routine (ISR)
- File System in Linux and Windows
OS Part-3
- Process and Process Control Block(PCB)
- Process Scheduling( Preemptive and Non Preemptive)
- Scheduling Algorithms
- Algorithm Evaluation
- Multiple Processor Scheduling
- Real Time Scheduling
- Operations on Processes
- Threads
- Inter-Process Communication
- Precedence Graphs
- Critical Section Problem
- Semaphores
- Classical Problems of Synchronization
- DeadLock
- Deadlock Prevention and Avoidance
- Deadlock Detection and Recovery
- Process Management in Linux
OS Part-4
- Memory Hierarchy in OS
- Concepts of Memory Management
- MFT and MVT
- Logical and Physical Address Space
- Swapping
- Contiguous and Non Contiguous Memory Allocation
- Paging
- Segmentation
- Paging Combined with Segmentation
- Structure and Implementation of Page Table
- Virtual Memory in OS
- Cache Memory Organization
- Demand Paging
- Page Replacement Algorithms
- Allocation of Frames and Thrashing
- Demand Segmentation
OS Part-5
- Distributed Operating System: Introduction and Types
- Distributed OS: Design Issues
- Distributed OS: File System
- Distributed OS: Remote File Access
- Remote Procedure Call(RPC)
- Remote Method Invocation(RMI)
- Distributed Shared Memory
- Parallel Processing and Concurrent Programming
- Security and Threats Protection in Distributed OS
- Security Design Principles and Authentication in Distributed OS
- Sensor Network and Parallel OS
Scheduler and Handler in Operating System
1. Device Driver Kya Hota Hai?
Device Driver ek software program hai jo Operating System (OS) aur hardware devices (jaise keyboard, printer, USB, hard disk) ke beech communication enable karta hai. Ye ek bridge ki tarah kaam karta hai jo OS ke high-level commands ko device-specific instructions me convert karta hai.
Scheduler aur Handler do important parts hote hain device driver ke, jo hardware requests manage karte hain:
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Device Scheduler – Ye I/O requests ko manage aur prioritize karta hai.
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Device Handler – Ye actual device operations perform karta hai.
Ye dono milkar ensure karte hain ki system efficiently kaam kare, koi process wait na kare aur hardware smoothly execute ho.
2. Device Scheduler
Device Scheduler Kya Hota Hai?
Device Scheduler ka kaam hota hai ki multiple I/O requests ka execution order decide kare taaki system fast aur efficient bane. Ye response time ko improve karta hai aur waiting time ko minimize karta hai.
Device Scheduler Ke Functions
Request prioritization – Kaunsa task pehle execute hoga ye decide karta hai. Faster response time – Jaldi wale requests ko pehle process karta hai. I/O performance optimize karta hai – Latency ko reduce karta hai. Starvation avoid karta hai – Har process ko fair chance deta hai.
Types of Scheduling Algorithms
First-Come, First-Serve (FCFS) Scheduling
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Jo request pehle aati hai, use pehle process kiya jata hai.
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Example: Ek printer queue me jo document pehle bheja gaya hai, wahi pehle print hoga.
Shortest Seek Time First (SSTF) Scheduling
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Jo request hard disk ke current position ke sabse kareeb hai, use pehle process kiya jata hai.
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Example: Hard disk ke andar jo file sabse paas hai, wahi pehle read hogi.
Elevator (SCAN) Scheduling
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Scheduler ek direction me move karta hai, sabhi requests complete karta hai, phir reverse hota hai.
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Example: Hard disk ka head ek elevator ki tarah left se right jata hai aur requests serve karta hai.
Round Robin Scheduling
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Har request ko ek fixed time slot milta hai aur cyclic order me process hoti hai.
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Example: Ek USB data transfer me multiple files ko equally transfer kiya jata hai.
Diagram: Device Scheduling Example
Requests: [98, 183, 37, 122, 14, 124, 65, 67]
3. Device Handler
Device Handler Kya Hota Hai?
Device Handler ka kaam hota hai actual I/O operations execute karna. Ye hardware aur OS ke beech directly interact karta hai aur ensure karta hai ki jo request scheduler ne bheji hai, wo sahi tarike se execute ho.
Functions of Device Handler
I/O requests ko receive karta hai – OS se commands leta hai. Device pe operations execute karta hai – Read/write operations karta hai. Errors handle karta hai – Agar device me koi issue ho toh fix karta hai. Efficient data transfer ensure karta hai – Buffering aur caching use karta hai.
Example of Device Handler in Action
User ne print command diya. Scheduler decide karega ki print job kab process hogi. Handler printer ko actual print command bhejega aur paper print karega.
Diagram: Device Handler Process Flow
[User Request] → [Scheduler] → [Handler] → [Device Execution]
4. Conclusion
Device Scheduler decide karta hai ki kaunsa I/O request pehle execute hoga. Device Handler ensure karta hai ki actual operation smoothly ho aur errors handle kiye jayein. Dono milkar OS aur hardware ke beech efficient communication enable karte hain.