Process of operating system

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Process of operating system

  1. 1. Process Ateeq zada khan 03002121899
  2. 2. What is a Process? • A process is a program during execution. • A process is the basic unit of execution in an operating system. • Different processes may run different instances of the same program. • At a minimum, process execution requires following resources: • Memory to contain the program code and data. • A set of CPU registers to support execution.
  3. 3. Process Creation • The OS builds a data structure to manage the process. • Traditionally, the OS created all processes • But it can be useful to let a running process create another. • This action is called process spawning • Parent Process is the original, creating process. • Child Process is the new process.
  4. 4. Process Termination • There must be some way that a process can indicate completion. • This indication may be: • A HALT instruction generating an interrupt alert to the OS. • A user action (e.g. log off, quitting an application) • A fault or error • Parent process terminating
  5. 5. Process Life Cycle • Processes are always either executing, waiting to execute or blocked waiting for an event to occur. • As a process executes, it changes state: • • • • • new: The process is being created. running: Instructions are being executed. waiting: The process is waiting for some event to occur. ready: The process is waiting to be assigned to a processor terminated: The process has finished execution.
  6. 6. Five State Process Model
  7. 7. Two Queues Diagram
  8. 8. Multiple Blocked Queues
  9. 9. Suspended Processes • Processor is faster than I/O so all processes could be waiting for I/O device. • Swap these processes to disk to free up more memory and use processor on more processes.. • Blocked state becomes suspend state when swapped to disk. • Two new states • Blocked/Suspend • Ready/Suspend
  10. 10. One Suspend State
  11. 11. Two Suspend States
  12. 12. Reasons • Swapping: • The OS need to make space for execute the process that in ready state. • OS Reason: • Operating system suspects the process faulty or causing a problem.
  13. 13. Questions ?

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