Processes Flashcards
What is a process?
A running program.
What is virtualisation?
When we give the impression that we are running multiple processes at the same time.
What is time-sharing? What is its cost?
This is when we run one process, then swap to another after a certain period of time. The cost is that each process will perform slightly worse.
What is a policy?
An algorithm which makes a decision for the OS, for example a scheduling policy like shortest-time-to-completion-first.
What is a process’s address space?
The memory which a process is able to access and address.
What are the stages of creating a process?
A program initially resides on the disk (persistent storage), and must be loaded into its address space by the OS. This may be done all at once, or more likely lazily as the code is needed. The OS must also allocate memory in the run-time stack for the program. It may also allocate some memory in the program’s heap. Finally, the OS will perform some IO setup.
What are the three states which a process can be in?
Running, Ready, Blocked.
How do we keep track of which processes we have?
With a process control block.
