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CS300 Technical Paper Summary-Borkar Pranay Shrihari (14189) Lecture Notes for Memory management Source-Class lecture for CS330 by Prof. Mainak Chaudh...

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CS300 Technical Paper Summary -Borkar Pranay Shrihari (14189) Lecture Notes for Memory management Source-Class lecture for CS330 by Prof. Mainak Chaudhuri • Process: – A Program in execution – Present in RAM • Many process need to share the Random Access memory. Various models are introduced for this purpose – Single contigious Model ∗ one process occupies RAM at a time ∗ No sharing of RAM ∗ Process memory size restricred by RAM size – Partition model ∗ ∗ ∗ ∗ ∗ ∗ ∗

Many process occupy ram Partition table is required Partition table =¿ —Base address—Size—Process—usage— Entries can be made dynamically Also can be freed dynamically which may lead to defragmentation Many algorithms for entering data first fit best fit

– Virtual Memory ∗ ∗ ∗ ∗ ∗

split RAM into page frames(usually 4KB) split processes also into small parts of page frame size there should be table per process that maps from process blocks to page frame number active the page table corresponding to active process which changes during context switch No need to load all memory

– Demand Paging ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗

Pages are loaded from disk to RAM only when needed Present bit in page table If on accessing present bit is page fault occurs Page replacement algorithms: first in first out least recently used least frequently used dirty bit is set if there are changes in pages in RAM

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