Day 01Part 16- Scheduling Queue in Operating System, Job Queue, Ready Queue and Device Queue

Here is a comprehensive breakdown of:

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🖥️ Day 01 – Part 16: Scheduling Queues in Operating System

📚 Topic: Job Queue, Ready Queue, Device Queue
👨‍💻 For: GATE / B.Tech / Operating System Fundamentals

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🎯 What are Scheduling Queues?

In an operating system, scheduling queues are used to manage processes during their life cycle. At any time, a process is in one of several queues depending on its state.

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🔁 Types of Scheduling Queues

1️⃣ Job Queue

• Contains all processes in the system.

• Includes processes that are:

  • New (not yet admitted)

  • Waiting for CPU

  • Performing I/O

• Think of it as the master list of all jobs submitted to the OS.

🧠 Example: When a process is created, it enters the job queue first.

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2️⃣ Ready Queue

• Holds all processes that are ready to execute but are waiting for CPU.

• Managed by the short-term scheduler.

• These are loaded into main memory (RAM).

🧠 Example: When a process has all the resources except CPU, it waits in the ready queue.

✅ Key Point: Only one process gets CPU at a time; others wait here.

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3️⃣ Device Queue (I/O Queue)

• Contains processes waiting for an I/O device (printer, disk, etc.).

• Each I/O device has its own queue.

• Handled by the device scheduler.

🧠 Example: If a process needs to read from disk, it is moved to the disk’s device queue.

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🧮 Process State Transitions and Queues:

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🧠 Summary Table:

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🎓 Quiz: Test Your Understanding

1. A process is moved from the ready queue to CPU. What is this action called?

   • A) Interrupt

   • B) Dispatch ✅

   • C) Admit

   • D) Block

2. Which queue holds processes waiting for I/O?

   • A) Job Queue

   • B) Ready Queue

   • C) Device Queue ✅

   • D) None

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📘 GATE Tip:

• Questions often ask “Which queue does a process move to after an I/O request?”

  • Answer: Device Queue

• Also expect diagrams, state transitions, and MCQs on scheduler types.

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Would you like:

• 🎥 A video explanation script?

• 📝 GATE-level MCQs PDF?

• 📊 Interactive flowchart or animation for learning?

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Day 01Part 16- Scheduling Queue in Operating System, Job Queue, Ready Queue and Device Queue.

CSC 553 Operating Systems Types of Scheduling

Process Scheduling