The Dispatching Role of Operating Systems
As should now be clear, this view of the operating system as a dispatcher
involves the moving of processes from one execution state to another.
The process's state is reflected by where it resides,
although its state will also record much other information.
The possible state transitions that we have now discussed are:
| Null → New |
a new process is requested.
|
| New → Ready |
resources are allocated for the new process.
|
| Ready → Running |
a process is given a time quantum.
|
| Running → Ready |
a process's execution time quantum expires.
|
| Running → Blocked |
a process requests slow I/O.
|
| Blocked → Ready |
an I/O interrupt signals that I/O is ready.
|
| Running → Exit |
normal or abnormal process termination.
|
| Ready or Blocked → Exit |
external process termination requested. |
CITS2002 Systems Programming, Lecture 7, p12, 14th August 2023.
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CITS2002