vault backup: 2022-11-01 13:04:33

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Jet Hughes 2022-11-01 13:04:33 +13:00
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# Swapping and virtual memory
swapping
- if there is not enough physical memory we need to sawp processes out of the main ememory to the secondary storage e.g., disk
- ![slide](https://i.imgur.com/ImjjXkb.png)
- when a process is ready, it is swapped into the main memory
- allows more processes to multitask
partially loaded proceses
- dynamic loading
- load a potion of code when it is called as some code may not need to be executed, e.g., code for handling errors
- pros
- process not limited by amount of avilable memory
- more processes multitasking
- quicker to swap than entire process
virtual memory
- idea that processes dont need to be fully in memory to run
extends main memory to secondary storage, and allows dynamic loading of processes while they execute
- programmer deals with vmem just like paging scheme
- mem manager in OS kernel controls loading pages of the process into main mem from secondary storage
# Demand paging