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SE 350
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Chapter 3
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- Recall what a process is
- Elements of a process
  - Identifier (PID)
  - State
  - Priority
  - Memory Pointers (pointers + shared memory blocks)
  - Context data (registers, PSW, program counter)
  - I/O status (I/O requests and devices in use)
  - Accounting information (processor time, time limits and threads)

- Process Control Block (PCB):
  - Data structure that contains the process elements
  - Created and managed by the OS
  - Allows support for multiple processes
  - Users may manipulate PCB partially by setting priority
  - Varies between OSs
- Trace of the Process: sequence of instruction that execute for a process
- Dispatcher: switches the processor from one processor to another

- Five state process model:
  - Running: process currently being executed
  - Ready: process that can be executed
  - Blocked/Waiting: process that cannot execute because it's waiting for something
  - New: a new process to enter the system
  - Exit: a halted or aborted process
- Use multiple queues for multiple event type waiting processes
- Suspened process:
  - Swap blocked processes to disk to free up memory
  - Blocked state becomes suspend state when swapped to disk
  - Add two new states: Suspend/ready, Suspend/blocked