Y.IE memory

testBase Bounds

mmuhardware

segmental Jer segment

Paging base bounds

Virtual Address Space

sized96

n smallÉ

fgjÉ

instantmad

a

f7y

4095

callintoos

growtyg

Realistic 32 bit virtualadd r space

kits I KB r 1000

zotbis 31 MB r million

zits I GB billion

Problems w segmentationexternal

feting becomes

full of small used spotsfree spots intermixed

phys memorynot fully flexiblee g sparse heap

Kdf

JggthnJIti.eunused

keep in 2gfree

memory 3 free

internal fragmentation

New approach Pagingdivide virtual address space

e g 4KBinto small fixed sized units

called pagetsimilarly divide phys mem

into yes pageframesvirt as I

me

IEEE an

É É

easye.g free list

Address1 I dd

n

Translation virtual addr

phys a ddr

e g virtual address space 32 bit

page size IIIB n

how many pages2

1 IÉT

III ge16 bytes virtual

address space

virt AddressÉtEEEEEM

Is Wapgettfset

A 8 8

Q

01 00

Q0110Problem too many pages

f 220 PE proda lot of information

where to store

Lain memoymanaged by

Os

in a data structure

called page table

store virtual physpage translations

page tablefor process store up to

8 translations

ÉÉÉÉÉw0I 21 I

2 O

O

yI 11

4naturally ssupports 6 8sparse 7 100 Iadd r space

First page table linear IggVPN arrayindex

47ft page tableentitiesto

istranslation

Bis bit

e.qfpp.ge're

virtual address

tfvirtIÉÉj.tt

s number

VAN

Ihardware badges of page tableVPN

I VPN x size of Effy

load PTE from memoryextract PFIform full phys add r PA

PA PFN offS

go to my for accest

Stowextra men

ref per mem ref