[Day 3] 1. Revision

Process Control Block (PCB) in Linux

• The
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  task_struct

  is a structure used to create the Process Control Block (PCB).
  • The size of a
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    task_struct

    can range from 4 to 5 KB or more.
  • Knowing about
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    task_struct

    and its role in PCB creation is useful as general knowledge.

Alternate Names for PCB:

• PCB: Process Control Block
• Process Descriptor
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  uarea

  (Unix-specific term)

Viewing Process Information in Linux:

• The command
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  ps -e

  lists information about all processes currently inside RAM.

OS Data Structures for Process Management:

1. Job Queue (Process List):

   • Contains all the processes currently loaded in memory (RAM).

2. Ready Queue:

   • Contains all processes that are ready for execution.

3. Waiting Queues:

   • Contains processes that are waiting after being interrupted.
   • There are multiple waiting queues for various devices, whereas there is only one job queue and one ready queue.
   • Each device (e.g., printer) has its own waiting queue. When a task for a device is completed, the next process from that device's waiting queue is executed.