Paging

Paging - Operating Systems Simple/Basic Paging Real Memory...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Operating Systems Simple/Basic Paging
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Real Memory Management Background Memory Management Requirements Fixed/Static Partitioning Variable/Dynamic Partitioning Simple/Basic Paging Simple/Basic Segmentation Segmentation with Paging
Background image of page 2
3 (Simple/Basic Paging (1 Idea: logical address space of a process can be made noncontiguous; process is allocated physical memory whenever the latter is available. Divide physical memory into fixed-sized chunks/blocks called frames (size is power of 2, usually between 512 bytes and 8192 bytes). Divide logical memory into blocks of same size called pages .
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 (Simple/Basic Paging (2 The process pages can thus be assigned to any available frames in main memory; a process does not need to occupy a contiguous portion of physical memory. Need to set up a page table to translate logical to physical pages/addresses. Internal fragmentation possible (for page at end of program).
Background image of page 4
5 Paging Example
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 (Simple/Basic Paging (3 To run a program of size n pages, need to find any n free frames and load all the program (pages). So need to keep track of all free frames in physical memory – use free-frame list. Free-frame list example in next slide.
Background image of page 6
7 Free-Frame list example Before allocation After allocation
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
8 (Example of processes loading (1 Now suppose that process B is swapped out.
Background image of page 8
9 (Example of processes loading (2 When process A and C are blocked, the pager loads a new process D of 5 pages. Process D does not occupy a contiguous portion of memory. There is no external fragmentation. Internal fragmentation can happen only in the last page of each process.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
(Example of processes loading (3 The OS now needs to maintain (in main memory) a page table for each process. Each entry of a page table consists of the frame number where the corresponding page is physically located. The corresponding page table is indexed by the page
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/15/2011 for the course ECO 2023 taught by Professor Mr.raza during the Summer '10 term at FAU.

Page1 / 33

Paging - Operating Systems Simple/Basic Paging Real Memory...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online