Khoa KTMT 1

Chng 7. Quan ly bo nh

Khai niem c s

Cac kieu a ch nh (physical address , logical

address)

Chuyen oi a ch nh

Overlay va swapping

Mo hnh quan ly bo nh n gian

Fixed partitioning

Dynamic partitioning

C che phan trang (paging)

C che phan oan (segmentation)

Segmentation with paging

Khoa KTMT 2

Khai niem c s

Chng trnh phai c mang vao trong bo nh va at

no trong mot tien trnh e c x ly

Input Queue Mot tap hp cua nhng tien trnh tren a ma ang ch e c mang vao trong bo nh e thc

thi.

User programs trai qua nhieu bc trc khi c x ly.

Khoa KTMT 3

Khai niem c s

Quan ly bo nh la cong viec cua he ieu hanh vi s ho

tr cua phan cng nham phan phoi, sap xep cac process

trong bo nh sao cho hieu qua.

Muc tieu can at c la nap cang nhieu process vao bo

nh cang tot (gia tang mc o a chng)

Trong hau het cac he thong, kernel se chiem mot phan co

nh cua bo nh; phan con lai phan phoi cho cac process.

Cac yeu cau oi vi viec quan ly bo nh

Cap phat bo nh cho cac process

Tai nh v (relocation): khi swapping,

Bao ve: phai kiem tra truy xuat bo nh co hp le khong

Chia se: cho phep cac process chia se vung nh chung

Ket gan a ch nh luan ly cua user vao a ch thc

Khoa KTMT 4

Cac kieu a ch nh

a ch vat ly (physical address) (a ch thc) la mot v

tr thc trong bo nh chnh.

a ch luan ly (logical address) la mot v tr nh c

dien ta trong mot chng trnh ( con goi la a ch ao

virtual address)

Cac trnh bien dch (compiler) tao ra ma lenh chng trnh ma trong o moi tham chieu bo nh eu la a ch luan ly

a ch tng oi (relative address) (a ch kha tai nh v, relocatable address) la mot kieu a ch luan ly trong o cac a

ch c bieu dien tng oi so vi mot v tr xac nh nao o

trong chng trnh.

V du: 12 byte so vi v tr bat au chng trnh,

a ch tuyet oi (absolute address): a ch tng ng vi a ch thc.

Khoa KTMT 5

Nap chng trnh vao bo nh

Bo linker: ket hp cac object module thanh mot file nh

phan kha thc thi goi la load module.

Bo loader: nap load module vao bo nh chnh

System

library

System

library

static linking

dynamic linking

Khoa KTMT 6

C che thc hien linking

Module A

CALL B

Return

length L

Module B

CALL C

Return

length M

Module C

Return

length N

0

L 1

Module A

JMP L

Return

Module B

JMP L+M

Return

Module C

Return

L

L M 1

L M

L M N 1

relocatable

object modules

load module

0

L 1

0

M 1

0

N 1

Khoa KTMT 7

Chuyen oi a ch

Chuyen oi a ch: qua trnh anh xa mot a ch t khong

gian a ch nay sang khong gian a ch khac.

Bieu dien a ch nh

Trong source code: symbolic (cac bien, hang, pointer,)

Thi iem bien dch: thng la a ch kha tai nh v

V du: a v tr 14 bytes so vi v tr bat au cua module.

Thi iem linking/loading: co the la a ch thc. V du: d lieu nam tai a ch bo nh thc 2030

0

250

2000

2250

relocatable addressphysical memory

symbolic address

int i;goto p1;

p1

Khoa KTMT 8

Chuyen oi a ch (tt)

a ch lenh (instruction) va d lieu (data) c chuyen oi

thanh a ch thc co the xay ra tai ba thi iem khac nhau

Compile time: neu biet trc a ch bo nh cua chng trnh th

co the ket gan a ch tuyet oi luc bien dch.

V du: chng trnh .COM cua MS-DOS

Khuyet iem: phai bien dch lai neu thay oi a ch nap chng trnh

Load time: Vao thi iem loading, loader phai chuyen oi a ch

kha tai nh v thanh a ch thc da tren mot a ch nen (base

address).

a ch thc c tnh toan vao thi iem nap chng trnh phai

tien hanh reload neu a ch nen thay oi.

Khoa KTMT 9

Sinh a ch tuyet oi vao thi iem dch

Symbolic

addresses

PROGRAM

JUMP i

LOAD j

DATA

i

j

Source code

Absolute

addresses

1024

JUMP 1424

LOAD 2224

1424

2224

Absolute load module

Compile Link/Load

Physical memory

addresses

1024

JUMP 1424

LOAD 2224

1424

2224

Process image

Khoa KTMT 10

Sinh a ch thc vao thi iem nap

Relative

(relocatable)

addresses

0

JUMP 400

LOAD 1200

400

1200

Relative

load module

Symbolic

addresses

PROGRAM

JUMP i

LOAD j

DATA

i

j

Source code

Compile Link/Load

Physical memory

addresses

1024

JUMP 1424

LOAD 2224

1424

2224

Process image

Khoa KTMT 11

Chuyen oi a ch (tt)

Execution time: khi trong qua trnh

thc thi, process co the c di

chuyen t segment nay sang

segment khac trong bo nh th qua

trnh chuyen oi a ch c tr

hoan en thi iem thc thi

Can s ho tr cua phan cng cho viec anh xa a ch.

V du: trng hp a ch luan ly la relocatable th co the dung

thanh ghi base va limit,

S dung trong a so cac OS a dung (general-purpose) trong o

co cac c che swapping, paging,

segmentation

Relative (relocatable)

addresses

0

JUMP 400

LOAD 1200

400

1200

MAX = 2000

Khoa KTMT 12

Khong gian a ch

a ch c tao bi CPU a ch logic (logical address). Tap hp a ch logic goi la khong gian a ch logic

a ch nap vao MAR a ch vat ly (physical address). Tap hp a ch vat ly goi la khong gian a ch vat ly

compile-time and load-time:

a ch Logical va physical la xac nh

Tai thi iem thc thi:

a ch logic khac vat ly, thng goi la a ch ao

Viec anh xa gia hai a ch c thc thi bi Memory Management

Unit (MMU)

Khoa KTMT 13

MMU

Tai nh v s dung relocation register

memoryCPU

relocation

register

+logical

address

642

physical

address

7642

7000

Khoa KTMT 14

Lien ket ong(Dynamic linking)

Qua trnh link en mot module ngoai (external module)

c thc hien sau khi a tao xong load module (i.e. file

co the thc thi, executable)

V du trong Windows: module ngoai la cac file .DLL con trong Unix, cac module ngoai la cac file .so (shared library)

Load module cha cac stub tham chieu (refer) en

routine cua external module.

Luc thc thi, khi stub c thc thi lan au (do process goi routine lan au), stub nap routine vao bo nh, t thay the bang

a ch cua routine va routine c thc thi.

Cac lan goi routine sau se xay ra bnh thng

Stub can s ho tr cua OS (nh kiem tra xem routine a

c nap vao bo nh cha).

Khoa KTMT 15

u iem cua dynamic linking

Thong thng, external module la mot th vien cung cap

cac tien ch cua OS. Cac chng trnh thc thi co the

dung cac phien ban khac nhau cua external module ma

khong can sa oi, bien dch lai.

Chia se ma (code sharing): mot external module ch can

nap vao bo nh mot lan. Cac process can dung external

module nay th cung chia se oan ma cua external

module tiet kiem khong gian nh va a.

Phng phap dynamic linking can s ho tr cua OS

trong viec kiem tra xem mot thu tuc nao o co the c

chia se gia cac process hay la phan ma cua rieng mot

process (bi v ch co OS mi co quyen thc hien viec

kiem tra nay).

Khoa KTMT 16

Nap ong(Dynamic loading)

C che: ch khi nao can c goi en th mot thu tuc mi

c nap vao bo nh chnh tang o hieu dung cua bo

nh (memory utilization) bi v cac thu tuc khong c

goi en se khong chiem cho trong bo nh

Rat hieu qua trong trng hp ton tai khoi lng ln ma

chng trnh co tan suat s dung thap, khong c s

dung thng xuyen (v du cac thu tuc x ly loi)

Ho tr t he ieu hanh

Thong thng, user chu trach nhiem thiet ke va hien thc cac chng trnh co dynamic loading.

He ieu hanh chu yeu cung cap mot so thu tuc, th vien ho tr, tao ieu kien de dang hn cho lap trnh vien.

Khoa KTMT 17

C che phu lap (overlay)

Tai moi thi iem, ch gi lai trong bo nh nhng

lenh hoac d lieu can thiet, giai phong cac

lenh/d lieu cha hoac khong can dung en.

C che nay rat hu dung khi kch thc mot

process ln hn khong gian bo nh cap cho

process o.

C che nay c ieu khien bi ngi s dung

(thong qua s ho tr cua cac th vien lap trnh)

ch khong can s ho tr cua he ieu hanh

Khoa KTMT 18

Pass 1 70K

Pass 2 80K

Symbol table 20K

Common routines 30K

Assembler

Total memory

available = 150KB

C che overlay (tt)

symbol

table20K

common

routines30K

overlay

driver10K

pass 1 pass 2

80K70K

n v: byte

nap va thc thi

Khoa KTMT 19

C che hoan v (swapping)

Mot process co the tam thi b swap ra khoi bo nh

chnh va lu tren mot he thong lu tr phu. Sau o,

process co the c nap lai vao bo nh e tiep tuc qua

trnh thc thi.

Swapping policy: hai v du

Round-robin: swap out P1

(va tieu thu het quantum cua no),

swap in P2 , thc thi P

3,

Roll out, roll in: dung trong c che nh thi theo o u tien (priority-based scheduling)

Process co o u tien thap hn se b swap out nhng cho cho process co o u tien cao hn mi en c nap vao bo

nh e thc thi

Hien nay, t he thong s dung c che swapping tren

Khoa KTMT 20

Minh hoa c che swapping

Khoa KTMT 21

Mo hnh quan ly bo nh

Trong chng nay, mo hnh quan ly bo nh la mot mo

hnh n gian, khong co bo nh ao.

Mot process phai c nap hoan toan vao bo nh th

mi c thc thi (ngoai tr khi s dung c che overlay).

Cac c che quan ly bo nh sau ay rat t (hau nh

khong con) c dung trong cac he thong hien ai

Phan chia co nh (fixed partitioning)

Phan chia ong (dynamic partitioning)

Phan trang n gian (simple paging)

Phan oan n gian (simple segmentation)

Khoa KTMT 22

Phan manh (fragmentation)

Phan manh ngoai (external fragmentation)

Kch thc khong gian nh con trong u e thoa man mot yeu cau cap phat, tuy nhien khong gian nh nay khong

lien tuc co the dung c che ket khoi (compaction) e gom lai thanh vung nh lien tuc.

Phan manh noi (internal fragmentation)

Kch thc vung nh c cap phat co the hi ln hn vung nh yeu cau.

V du: cap mot khoang trong 18,464 bytes cho mot process yeu cau 18,462 bytes.

Hien tng phan manh noi thng xay ra khi bo nh thc c chia thanh cac khoi kch thc co nh (fixed-sized

block) va cac process c cap phat theo n v khoi. V

du: c che phan trang (paging).

Khoa KTMT 23

Phan manh noi

operating

system

(used)

yeu cau ke tiep la

18,462 bytes !!!

hole kch thc

18,464 bytescan quan ly khoang

trong 2 bytes !?!

OS se cap phat han khoi 18,464 bytes

cho process d ra 2 bytes khong dung!

Khoa KTMT 24

Fixed partitioning

Khi khi ong he thong, bo nh chnh

c chia thanh nhieu phan ri nhau

goi la cac partition co kch thc bang

nhau hoac khac nhau

Process nao co kch thc nho hn

hoac bang kch thc partition th co

the c nap vao partition o.

Neu chng trnh co kch thc ln

hn partition th phai dung c che

overlay.

Nhan xet

Khong hieu qua do b phan manh noi: mot chng trnh du ln hay nho eu

c cap phat tron mot partition.

Khoa KTMT 25

Chien lc placement (tt)

Partition co kch thc bang nhau

Neu con partition trong process mi se c nap vao partition o

Neu khong con partition trong, nhng trong o co process ang b

blocked swap process o ra bo

nh phu nhng cho cho process

mi.

Partition co kch thc khong bang

nhau: giai phap 1

Gan moi process vao partition nho nhat phu hp vi no

Co hang i cho moi partition

Giam thieu phan manh noi

Van e: co the co mot so hang i trong khong (v khong co process

vi kch thc tng ng) va hang

i day ac

Khoa KTMT 26

Chien lc placement (tt)

Partition co kch thc khong

bang nhau: giai phap 2

Ch co mot hang i chung cho moi partition

Khi can nap mot process vao bo nh chnh chon partition

nho nhat con trong

Khoa KTMT 27

Dynamic partitioning

So lng partition khong co nh va partition co the co

kch thc khac nhau

Moi process c cap phat chnh xac dung lng bo nh

can thiet

Gay ra hien tng phan manh ngoai

Khoa KTMT 28

Chien lc placement

Dung e quyet nh cap phat

khoi bo nh trong nao cho

mot process

Muc tieu: giam chi ph

compaction

Cac chien lc placement

Best-fit: chon khoi nh trong nho nhat

First-fit: chon khoi nh trong phu hp au tien ke t au

bo nh

Next-fit: chon khoi nh trong phu hp au tien ke t v tr

cap phat cuoi cung

Worst-fit: chon khoi nh trong ln nhat

Bi Tp

Gi s b nh chnh c phn thnh cc phn vng c kch

thc l 600K, 500K, 200K, 300K ( theo th t ), cho bit cc tin

trnh c kch thc 212K, 417K, 112K v 426K ( theo th t ) s

c cp pht b nh nh th no, nu s dng :

a) Thut ton First fit

b) Thut ton Best fit

c) Thut ton Worst fit

d) Thut ton Next fit

Thut ton no cho php s dng b nh hiu qa nht trong trng

hp trn ?

Khoa KTMT 29

Khoa KTMT 30

Cap phat khong lien tuc

1.C che phan trang (paging)

Bo nh vat ly khung trang (frame). Kch thc cua frame la luy tha cua 2, t khoang 512 byte en

16MB.

Bo nh luan ly (logical memory) hay khong gian a ch

luan ly la tap moi a ch luan ly ma mot chng trnh

bat ky co the sinh ra page. V du

MOV REG,1000 //1000 la mot a ch luan ly

Bang phan trang (page table) e anh xa a ch luan ly

thanh a ch thc

Khoa KTMT 31

1.C che phan trang (tt)

logical memory

1

4

3

5

0

1

2

3

page table

page 0

page 2

physical memory

framenumber

0

1

2

3

page 14

5 page 3

pagenumber

0

1

2

3

Khoa KTMT 32

1.C che phan trang (tt)

A) Chuyen oi a ch trong paging

a ch luan ly gom co:

So hieu trang (Page number) p

a ch tng oi trong trang (Page offset) d

Neu kch thc cua khong gian a ch luan ly la 2m, va kch

thc cua trang la 2n

(n v la byte hay word tuy theo kien truc

may) th

Bang phan trang se co tong cong 2m/2

n= 2

m nmuc (entry)

p d

page number page offset

m n bits

(nh v t 0 2m n 1)

n bits

(nh v t 0 2n 1)

Khoa KTMT 33

1.C che phan trang (tt)

CPU p d f d

f

p

page table

logical

address

physical

address

physical

memory

f 0000

f 1111

f framesA) Chuyen oi a ch trong paging

Khoa KTMT 34

1.C che phan trang (tt)

V du: Chuyen oi a ch nh trong paging

V d

Xt mt khng gian a ch c 8 trang, mi

trang c kch thc 1KB. nh x vo b nh

vt l c 32 khung trang

a) a ch logic gm bao nhiu bit ?

b) a ch physic gm bao nhiu bit ?

c) Bng trang c bao nhiu mc?Mi mc

trong bng trang cn bao nhiu bit?

Khoa KTMT 35

Khoa KTMT 36

1.C che phan trang (tt)

Trc khi va sau khi cap phat cho Process mi

Khoa KTMT 37

B) Cai at bang trang (Paging hardware)

Bang phan trang thng c lu gi trong bo nh chnh

Moi process c he ieu hanh cap mot bang phan trang

Thanh ghi page-table base (PTBR) tro en bang phan trang

Thanh ghi page-table length (PTLR) bieu th kch thc cua bang phan trang (co the c dung trong c che bao ve bo nh)

Thng dung mot bo phan cache phan cng co toc o

truy xuat va tm kiem cao, goi la thanh ghi ket hp

(associative register) hoac translation look-aside buffers

(TLBs)

Khoa KTMT 38

B) Cai at bang trang (Paging hardware)

Dung thanh ghi Page-Table Base Register (PTBR)

p

Khoa KTMT 39

Paging hardware vi TLB

Khoa KTMT 40

C) Effective access time (EAT)

Tnh thi gian truy xuat hieu dung (effective access time,

EAT)

Thi gian tm kiem trong TLB (associative lookup):

Thi gian mot chu ky truy xuat bo nh: x

Hit ratio: t so gia so lan ch so trang c tm thay (hit)

trong TLB va so lan truy xuat khi nguon t CPU

K hieu hit ratio:

Thi gian can thiet e co c ch so frame

Khi ch so trang co trong TLB (hit) + x

Khi ch so trang khong co trong TLB (miss) + x + x

Thi gian truy xuat hieu dung

EAT = ( + x) + ( + 2x)(1 )

= (2 )x +

Khoa KTMT 41

C) Effective access time (EAT)

V du 1: n v thi gian

nano giay

Associative lookup = 20

Memory access = 100

Hit ratio = 0.8

EAT = (100 + 20) 0.8 +

(200 + 20) 0.2

= 1.2 100 + 20

= 140

V du 2

Associative lookup = 20

Memory access = 100

Hit ratio = 0.98

EAT = (100 + 20) 0.98 +

(200 + 20) 0.02

= 1.02 100 + 20

= 122

V d

Xt mt h thng s dng k thut phn trang, vi

bng trang c lu tr trong b nh chnh.

a) Nu thi gian cho mt ln truy xut b nh bnh

thng l 200nanoseconds, th mt bao nhiu thi

gian cho mt thao tc truy xut b nh trong h

thng ny ?

b) Nu s dng TLBs vi hit-ratio ( t l tm thy)

l 75%, thi gian tm trong TLBs xem nh bng

0, tnh thi gian truy xut b nh trong h thng (

effective memory reference time)

Khoa KTMT 42

Khoa KTMT 43

D) To chc bang trang - Phan trang a cap

Cac he thong hien ai eu ho tr khong gian a ch ao

rat ln (232

en 264

), ay gia s la 232

Gia s kch thc trang nh la 4KB (= 212)

bang phan trang se co 232/212 = 220 = 1M muc.

Gia s moi muc gom 4 byte th moi process can 4MB cho bang

phan trang

VD: Phan trang hai cap

P2 d

So trang o di trang

P1

10 bit 10 bit 12

Phn trang a cp (tt)

Khoa KTMT 44

Khoa KTMT 45

D) To chc bang trang

Phan trang a cap

Khoa KTMT 46

D) To chc bang trang

Bang trang nghch ao: s dung cho tat ca cac Process

i

Khoa KTMT 47

E) Bao ve bo nh

Viec bao ve bo nh c hien thc bang cach gan vi

frame cac bit bao ve (protection bits) c gi trong

bang phan trang. Cac bit nay bieu th cac thuoc tnh sau

read-only, read-write, execute-only

Ngoai ra, con co mot valid/invalid bit gan vi moi muc

trong bang phan trang

valid: cho biet la trang cua process, do o la mot trang hp le.

invalid: cho biet la trang khong cua process, do o la mot trang

bat hp le.

Khoa KTMT 48

Bao ve bang valid/invalid bit

Moi trang nh co kch thc 2K = 2048

Process co kch thc 10,468 phan manh noi frame 9 (cha page 5), cac a ch ao > 12287 la cac a ch invalid.

Dung PTLR e kiem tra truy xuat en bang phan trang co nam trong bang hay khong.

00000

10468

12287

2 v

3 v

4 v

7 v

8 v

9 v

0 i

0 i

frame

number

valid/

invalid bit

0

1

2

3

4

5

6

7

0

1

2 page 0

3 page 1

4 page 2

5

6

7 page 3

8 page 4

9 page 5

...

page n

16383

14 bit

Khoa KTMT 49

F) Chia se cac trang nh

Process 1

ed 1

ed 2

ed 3

data 1

ed 1

ed 2

ed 2

data 3

Process 3

3

4

6

2

0

1

2

3

3

4

6

1

0

1

2

3

Process 2

ed 1

ed 2

ed 3

data 2

3

4

6

7

0

1

2

3

0

1 data 1

2 data 3

3 ed 1

4 ed 2

5

6 ed 3

7 data 2

8

9

10

Bo nh thc

Khoa KTMT 50

2.Phan oan (segmentation)

Nhn lai c che phan trang

user view (khong gian a ch ao) tach biet vi khong gian bo nh thc. C che phan trang thc hien phep anh xa user-view

vao bo nh thc.

Trong thc te, di goc nhn cua user, mot chng trnh

cau thanh t nhieu oan (segment). Moi oan la mot n

v luan ly cua chng trnh, nh

main program, procedure, function

local variables, global variables, common block, stack, symbol table, arrays,

Khoa KTMT 51

User view cua mot chng trnh

Thong thng, mot chng trnh

c bien dch. Trnh bien dch

se t ong xay dng cac

segment.

V du, trnh bien dch Pascal se

tao ra cac segment sau:

Global variables

Procedure call stack

Procedure/function code

Local variable

Trnh loader se gan moi

segment mot so nh danh

rieng.

procedurestack

symbol

table

function

sqrt

main program

Logical address space

Khoa KTMT 52

Phan oan

Dung c che phan oan e quan ly bo nh co ho tr

user view

Khong gian a ch ao la mot tap cac oan, moi oan co ten va kch thc rieng.

Mot a ch luan ly c nh v bang ten oan va o di (offset) ben trong oan o (so sanh vi phan trang!)

Khoa KTMT 53

Phan oan (tt)

logical address space physical memory space

segment 1

segment 2

segment 3 segment 4

Khoa KTMT 54

Cai at phan oan

a ch luan ly la mot cap gia tr

(segment number, offset)

Bang phan oan (segment table): gom nhieu muc, moi

muc cha

base, cha a ch khi au cua segment trong bo nh

limit, xac nh kch thc cua segment

Segment-table base register (STBR): tro en v tr bang

phan oan trong bo nh

Segment-table length register (STLR): so lng segment

cua chng trnh

Mot ch so segment s la hp le neu s < STLR

Khoa KTMT 55

Mot v du ve phan oan

procedure

stack

symbol

table

function

sqrt

main program

segment 0

segment 3

segment 1segment 2

segment 4

procedure

stack

main

symbol table

function sqrt

limit base

0 1000 1400

1 400 6300

2 400 4300

3 1100 3200

4 1000 4700

segment

table

logical address spacephysical memory space

1400

2400

3200

4300

4700

5700

6300

Khoa KTMT 56

Phan cng ho tr phan oan

CPU

+physical

memory

no

trap; addressing error

limit base

s

s d

yes

segment

table

Khoa KTMT 57

Chuyen oi a ch trong c che phan oan

V du

Khoa KTMT 58

Chia se cac oan

editordata 1

segment 0segment 1

logical address space

process P1

editordata 2

segment 0segment 1

logical address space

process P2

limit base

0 25286 43062

1 4425 68348

segment table

process P1

limit base

0 25286 43062

1 8850 90003

segment table

process P2

editor

data 1

data 2

physical memory

43062

72773

68348

90003

98853

Khoa KTMT 59

3.Ket hp phan trang va phan oan

Ket hp phan trang va phan oan nham ket hp cac u

iem ong thi han che cac khuyet iem cua phan

trang va phan oan:

Van e cua phan oan: Neu mot oan qua ln th co the khong nap no c vao bo nh.

Y tng giai quyet: paging oan, khi o ch can gi trong bo nh cac page cua oan hien ang can.

Logic Addr =

Khoa KTMT 60

3.Ket hp phan trang va phan oan

Khoa KTMT 61

3.Ket hp phan trang va phan oan

Bi Tp

Xt mt khng gian c b nh lun l kch thc

1 trang l 1KB. Tnh s trang v di (offset)

ca tng a ch sau:

a) 2.375

b) 19.366

c) 30.000

d) 256

e) 16.385

Khoa KTMT 62

Bi Tp

Xt mt khng gian c b nh lun l c 64

trang, mi trang c 1024 t, mi t l 2 byte c

nh x vo b nh vt l c 32 trang:

a) a ch b nh vt l c bao nhiu bit?

b) a ch b nh lun l c bao nhiu bit?

c) C bao nhiu mc trong bng phn trang? Mi

mc cha bao nhiu bit?

Khoa KTMT 63

Bi tp

Xt mt h thng s dng k thut phn trang, vi

bng trang c lu tr trong b nh chnh.

a) Nu thi gian cho mt ln truy xut b nh bnh

thng l 100 nanoseconds, th mt bao nhiu thi

gian cho mt thao tc truy xut b nh trong h

thng ny ?

b) Nu s dng TLBs vi hit-ratio ( t l tm thy)

l 85%, thi gian tm trong TLBs l 20

nanosecond, tnh thi gian truy xut b nh trong

h thng ( effective memory reference time)

Khoa KTMT 64

Bi tp

Xt bng phn on sau y :

Cho bit a ch vt l tng ng vi cc a ch logic sau

y :

a. 0,430 b. 1,100 c. 2,500 d. 3,400 e. 4,112

Khoa KTMT 65

Segment Base Length

0 219 600

1 2300 14

2 90 100

3 1327 580

4 1952 96