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H iu hnh

Nguyn Trung ng

Tel. 0983 410 866

Email. [email protected]

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Ti liu tham kho chnh

T Minh Phng: Gio trnh H iu hnh. Hc Vin CNBCVT, H Ni 2013

Trn Hnh Nhi, Gio trnh HH nng cao, H Khoa hc T nhin Tp.HCM, 1998

Nguyn Gia nh-Nguyn Kim Tun, Nguyn L HH, NXB Khoa hc k thut, 2005

William Stallting, Operating Systems, Prentice Hall, 1995

Chng I:TNG QUAN V HH

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NI DUNG:

1.1 Khi nim v HH

1.2 Phn loi HH

1.3 Cu trc ca HH

1.4 Tm hiu v lch s pht trin ca HH

1.5 Gii thiu mt s HH ph bin hin nay

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1.1 KHI NIM V HH

H iu hnh l mt chng trnh hay mt h chng trnh phn mm my tnh, hot ng lp trung gian gia ngi s dng v phn cng my tnh

Mc tiu ca HH l cung cp mi trng ngi s dng: Thc thi cc chng trnh

S dng my tnh tr nn d dng, khai thc phn cng my tnh mt cch hiu qu

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1.1 KHI NiM V HH

HH l mt b phn quan trng ca h thng my tnh. Mt h thng my tnh bao gm 4 phn:

1) Phn cng: CPU; B nh; Cc thit b xut/nhp

2) H iu hnh

3) Cc chng trnh ng dng

4) i tng s dng: Ngi, thit b hoc my tnh khc

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84 Thnh phn ca h thng my tnh

Ngi sdng 1

Ngi sdng 2

Ngi sdng 3

Ngi sdng n

Cc chng trnh ng dng

H iu hnh

Phn cng

Trnh bin dch Hp ng Son tho vn bn CSDL

1.2 PHN LOI HH

H thng s l theo l n gin

H thng s l theo l a chng

H thng chia s thi gian

H thng song song

H thng phn tn

H thng x l thi gian thc

V.v.

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H THNG X L THEO L N GiN

Cc tc v c a vo hng i Thc hin cc tc v ln lt theo nhng

ch th c xc nh trcTc v tip theo t ng c thc hin

khi tc v trc kt thc 1 cch t ngC b gim st thng trc gim st

vic thc hin ca cc tc v trong h thngProcessor ri vo trng thi ch khi h thng truy xut thit b vo ra

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H THNG X L THEO L A CHNG

Thc hin c nhiu tc v ng thi

HH np 1 phn code v data ca tc v vo b nh

Khi c tc v ang s dng Processor thc hin truy xut thit b vo ra th Processor s c chuyn thc hin tc v khc

Cn c c ch lp lch cho Processor

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H THNG CHIA S THI GIAN

Cc tc v, tin trnh c s dng Processor lun phin nhau theo lch phn chia thi gian s dng Processor c lp (vi mt khong thi gian t rt nh)

Cung cp cho mi ngi s dng 1 phn nh trong my tnh chia s =>Ngi s dng c th yu cu my tnh thc hin ng thi nhiu cng vic

C c ch qun tr vo bo v b nh, s dng b nh o

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H THNG SONG SONG

C nhiu Processor trong cng mt h thng my tnh

Cc Processor cng chia s ng truyn d liu, ng h xung, b nh v cc thit b ngoi vi

C 2 loi HH a Processor:1) a x l i xng (Symmetric multiprocessing-

SMP)

2) a x l bt i xng (Asymmetric multiprocessing-ASMP)

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H THNG SONG SONG1) a x l i xng:

Mi Processor chy c lp trn mt bn sao HH nh nhau

Cho php nhiu tin trnh chy ng thi trn mt h thng

2) a x l bt i xng:

Mi Processor c giao mt nhim v ring bit

C mt hoc 2 Processor ch lm nhim v lp lch, xc nh cng vic cho cc Processor thnh vin

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H THNG PHN TN

Phn tn s tnh ton trn cc b x l vt l

Mi b x l c b nh cc b ring

Cc b x l thng tin vi nhau thng qua cc ng truyn thng tc cao

C 2 dng h thng: Client/Server v Peer-to-Peer

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H THNG X L THI GIAN THC

C kh nng cho kt qu tc thi, chnh xc sau mi tc v

Tc v cn thc hin khng a vo hng i m s l tc thi v tr li ngay kt qu chnh xc trong khong thi gian b thc p nhanh nht

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1.3 CU TRC CA HH

1.3.1 CC NHIM V CA HH

1. Qun l tin trnh

2. Qun l b nh chnh

3. Qun l Vo/Ra

4. Qun l b nh ph

5. Qun l tp tin

6. Thng dch lnh

7. Bo v h thng

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NHIM V QUN L TIN TRNH

a. To lp v hy b tin trnh

b. Tm dng v kch hot li tin trnh b tm dng

c. To c ch thng tin lin lc gia cc tin trnh

d. To c ch ng b ha gia cc tin trnh

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NHIM V QUN L B NH CHNH

1) Cp pht, thu hi vng nh

2) Ghi nhn trng thi b nh chnh

3) Bo v b nh

4) Quyt nh tin trnh no c np vo b nh

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NHIM V QUN L XUT/NHP

1) Lm cho cc thao tc trao i thng tin trn cc thit b Vo/Ra c trong sut vi ngi s dng

2) Mt h thng Vo/Ra bao gm:

H thng buffer caching.

B giao tip iu khin thit b.

B iu khin cho cc thit b c th.

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NHIM V QUN L B NH PH

1) Qun l khng gian trng trn a

2) nh v lu tr thng tin trn a

3) Lp lch cho vn ghi/c thng tin trn a ca u t

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NHIM V QUN L TP TIN

1) To/xa tp tin, th mc

2) Bo v tp tin khi c truy xut ng thi

3) Cung cp cc thao tc x l v bo v tp tin, th mc

4) To c ch truy xut tp tin thng qua tn tp tin,

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NHIM V THNG DCH LNH

1) ng vai tr giao tip gia HH v ngi s dng

2) Mt s HH thnh phn ny nm trong nhn ca n, mt s HH khc thit k di dng 1 chng trnh c bit

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NHIM V BO V H THNG

Kim sot qu trnh truy xut ca chng trnh, tin trnh, hoc ngi s dng vi ti nguyn ca h thng

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1.3. CU TRC CA HH

a. CU TRC N KHI:

L mt tp hp cc th tc, mi th tc c th gi thc hin mt th tc khc bt k lc no cn thit

MS-DOS l mt h iu hnh c cu trc n gin, n cung cp nhng chc nng ln nht cho h thng ti thiu

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CU TRC N KHI

CU TRC PHN LP

H thng c chia thnh mt s lp

Mi lp c xy dng da trn mt lp bn di

Lp di cng l phn cng, lp trn cng l giao din vi ngi s dng

Cu trc phn lp ca HH UNIX

Phn cng

H iu hnh Unix

Th vin chun

Chng trnh tin ch chun

Ngi s dng

CU TRC VI NHN

Vi cu trc vi nhn, phn nhn ch cha cc chc nng quan trng nht. Cc chc nng cn li ca h iu hnh c t chc thnh cc mun, c th hot ng trong ch u tin nh phn nhn hoc nh cc chng trnh ng dng thng thng. Mi khi c yu cu cung cp dch v t chng trnh ng dng, yu cu s c chuyn cho mun tng ng thc hin

CU TRC MY O

L bn sao chnh xc cc c tnh phn cng ca my tnh thc. c cung cp phn cng v kernel ca HH nh my tht

Ti nguyn my tnh vt l c chia s to ra cc my o

Mi tin trnh c thc hin trn mt my o c lp

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Trong mt h iu hnh, y l cc phn ct li cachng trnh, c tr trong b nh, v thc hin hu htcc nhim v iu hnh chnh, nh qun l cc thao tcvo ra a, v qun l b nh trong

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CU TRC CLIENT/SERVER Cc tin trnh c chia thnh 2 loi

Tin trnh Client: L cc tin trnh bn ngoi hay tin trnh ca chng trnh ngi s dng

Tin trnh Server: L cc tin trnh ca HH

Khi cn thc hin 1 chc nng ca h thng tin trnh client gi yu cu n tin trnh server tng ng, tin trnh server x l v tr v cho client

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1.4 LCH S PHT TRIN CA HH

1. Th h 1(1945-1955)

My tnh dng ng chn khng ra i

Vn hnh my tnh cn 1 nhm ngi: Thit k, xy dng chng trnh, thao tc, qun l,

Cha c khi nim v ngn ng lp trnh v HH

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2. Th h 2(1955-1965) My tnh dng bn dn ra i B phn s dng my tnh c phn chia r rng:

ngi thit k, ngi xy dng, ngi lp trnh, ngi vn hnh,

Ngn ng Assembly v Foxtran ra i Chng trnh c vit trn phiu c l H thng x l theo l ra i, cc yu cu thc hin

c lu trn bng t, h thng c v thi hnh ln lt

H thng x l theo l hot ng di s iu khin ca 1 chng trnh c bit

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3. Th h 3(1965-1980) My tnh c s dng rng ri Ra i my tnh IBM 360 s dng mch IC Thit b ngoi vi dng cho my tnh xut hin ngy

cng nhiu Cc thao tc iu khin my tnh ngy cng phc

tp HH ra i nhm iu , kim sot hot ng ca

h thng v gii quyt cc yu cu tranh chp thit b

Bt u c khi nim a chng, chia s thi gian thc v k thut spool

Xut hin HH Multics v Unix

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4. Th h 4(1980->)

My tnh c nhn ra i

HH MS-DOS ra i gn lin vi my tnh IBM PC

Ra i v pht trin nhiu HH gn lin vi s pht trin ca phn cng my tnh

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CHNG II:

QUN L TIN TRNH

1. TNG QUAN V TIN TRNH

1.1 Tin trnh (process)

Tin trnh l mt chng trnh ang c thc thi, c s hu 1 con tr lnh, tp cc thanh ghi v cc bin

hon thnh tc v ca mnh, mt tin trnh c th cn n mt s ti nguyn nh CPU, b nh chnh, cc tp tin v thit b Vo/Ra.

1.1 Tin trnh (process)

Tin trnh s hu 3 thnh phn: Code, Data, Stack

Code: Thnh phn cu lnh thc hin

Data: Thnh phn d liu

Stack: Thnh phn lu thng tin tm thi

Cc cu lnh trong code ch dng data v stack ring ca mnh ngoi tr cc vng dng chung

Tin trnh c h thng phn bit bng s hiu pid (proccess indentification)

Thng tin m t tin trnhH iu hnh cn c cc thng tin v tin trnh lu trong cu trc d liu PCB (Process Control Block), gm:- S nh danh ca tin trnh: tin trnh c gn mt s nh

danh PID cho php phn bit vi tin trnh khc. S nh danh ny c h iu hnh s dng tm v tr tng ng vi tin trnh trong bng tin trnh (xem phn sau), hoc s dng tham chiu gia cc bng khc nhau lu thng tin lin quan n tin trnh.

- Trng thi tin trnh: mt trong nm trng thi lit k phn trc.

- Ni dung mt s thanh ghi CPU: ni dung mt s thanh ghi quan trng nh: Thanh ghi con tr lnh, Thanh ghi con tr ngn xp, Cc thanh ghi iu kin v thanh ghi trng thi, Cc thanh ghi a dng khc.

- Thng tin phc v vic iu tin trnh- Thng tin v b nh ca tin trnh- Danh sch cc ti nguyn khc- Thng tin thng k phc v qun l

status

PID

Waiting/waiting list

CPU-state-rec

Processor

Main store

Resource

Created recource

Parent

Progency

Priority

CPU time

Unit 1 Unit 2

RCB 1 RCB 2

RCB 1 RCB 2

PCB

PCB 1 PCB 2

Ng cnh ca T-trnh

Thng tin giao tip

Thng tin thng k

Trng thi T-trnh

nh danh T-trnhCu trc d liu PCB

1.2 Cc trng thi ca tin trnh

Trng thi ca tin trnh ti mi thi im c xc nh bi hot ng hin thi ca n, tc l 1 trong cc trng thi sau: Mi: tin trnh c to lp

Sn sang: tin trnh sn sang, ang ch cp CPU

Chy (thc thi): tin trnh ang c x l

Ch i: tin trnh tm dng v ch cp phtti nguyn hay ch 1 s kin no

Kt thc: Tin trnh hon tt

M t chuyn trng thi ca tin trnh

Mi khi to Sn sng: tin trnh c khi to xong v c ti vo b nh, ch ch c cp CPU chy

Sn sng Chy: do kt qu iu ca h iu hnh, tin trnh c h iu hnh cp pht CPU v chuyn sang trng thi chy.

Chy Sn sng: h iu hnh cp pht CPU cho tin trnh khc do kt qu iu hoc do xy ra ngt, tin trnh hin thi chuyn sang trng thi sn sng v ch c cp CPU

Chy Ch i c d liu, hay thc hin li gi h thng, tin trnh chuyn sang trng thi ch i hoc cn gi l trng thi b phong ta (blocked).

Ch i Sn sng: khi s kin c ch i xy ra, tin trnh s c chuyn sang trng thi sn sng.

Chy Kt thc: tin trnh thc hin xong, c chuyn sang trng thi kt thc.

b

b

PCB ca cc tin trnh ang c trong h thng

c lin kt thnh thnh mt s danh sch, mi danh sch bao gm tin trnh c cng trng

thi hoc tin trnh ang cng ch i mt ti nguyn

1.3 Ch x l ca tin trnh

Tin trnh ca HH cn c bo v khi s xm phm ca tin trnh khc

Ch x l c chia thnh 2 ch nh s h tr ca phn cng: c quyn v khng c quyn

Tin trnh ca HH hot ng trong ch c quyn v ca ngi s dng hot ng trong ch khng c quyn

1.3 Ch x l ca tin trnh

Tp lnh ca CPU c chia thnh 2 tp

OS

Hardware

Shell, editor

users

Ch khng c quyn

Ch c quyn

1.4 Cc thao tc iu khin tin trnh

a. Khi to tin trnh HH gn PID v a vo danh sch qun l ca

h thng

Cp pht khng gian b nh

Khi to cc thng tin cn thit cho khi iu khin tin trnh: Cc PID ca p cha (nu c), thng tin trng thi, u tin, ng cnh ca processor

Cung cp y cc ti nguyn (tr processor)

a tin trnh vo danh sch p no : ready list, suspend list, waiting list

b. Kt thc tin trnh HH thc hin cc thao tc:

Thu hi ti nguyn cp pht cho p

Loi b tin trnh ra khi danh sch qun l ca h thng

Hy b khi iu khin p

c. Thay i trng thi ca p HH thc hin: Lu ng cnh ca processor

Cp nht PCB (process control block) ca tin trnh sao cho ph hp vi trng thi ca p

Di chuyn PCB ca p n 1 hng i thch hp

Chn tin trnh khc cho php n thc hin

Cp nht PCB ca p va thc hin

Cp nht thng tin lin quan n qun l b nh

Khi phc li ng cnh ca processor

Chuyn i ng cnh P0 P1

1.6 Tiu trnh (thread) Thng thng mi tin trnh c 1 khng gian

a ch v 1 dng x l

Mong mun c nhiu dng x l cng chia s 1 khng gian a ch v cc dng x l hot ng song song nh cc tin trnh c lp

Xut hin HH c c ch thc thi gi l tiu trnh

Tiu trnh l: 1 n v x l c bn

S hu 1 con tr lnh, tp cc thanh ghi, 1 vng nh stack ring

C cc trng thi nh tin trnh tht.

Trong m hnh n lung, tin trnh PCB cha y thng tin v trng thi tin trnh, gi tr cc thanh ghi, c ngn xp cha tham s v trng thi hm/th tc/chng trnh con khi thc hin chng trnh con.

Khi thc hin, tin trnh s lm ch ni dung cc thanh ghi v con tr lnh.

i vi m hnh a lung, do mi lung c chui thc hin ring ca mnh, mi lung cn c kh nng qun l con tr lnh, ni dung thanh ghi. Lung cng c trng thi ring nh

chy, b kha, sn sng.

Ti nguyn ca tin trnh v lung

Tin trnh l n v c h iu hnh s dng phn phi ti nguyn. Mi tin trnh v tt c cc lung thuc tin trnh s s hu chung

mt s s ti nguyn bao gm:

- Khng gian nh ca tin trnh. y l khng gian nh lgic, c th l khng gian nh o,

c s dng cha phn chng trnh (cc lnh), phn d liu ca tin trnh.

- Cc ti nguyn khc nh file do tin trnh m, thit b hoc cng vo/ra.

u im ca m hnh a lung1) Tng hiu nng v tit kim thi gian. Dng chung ti nguyn Vic chuyn i lung nhanh hn vi chc ln so vi to mi tin trnh.2) D dng chia s ti nguyn v thng tin. Ti nguyn dng chung cho php lung d dng lin lc vi nhau3) Tng tnh p ng. Tin trnh c th s dng mt lung thc hin nhng thao tc i hi nhiu thi gian nh c file di, s dng mt lung khc tip nhn v x l yu cu ca ngi dng, trnh cm gic tin trnh b treo.4) Tn dng c kin trc x l vi nhiu CPU, cc lung c th chy song song trn nhng CPU khc nhau, nh vy tng c tc x l chung ca tin trnh.

5) Thun li cho vic t chc chng trnh. Mt s chng trnh c th t chc d dng di dng nhiu lung thc hin ng thi.

Lung mc ngi dng: do trnh ng dng t to ra v qun l, h iu hnh khng bit v s tn ti ca nhng lung nh vy. u im: Vic chuyn i lung khng i hi phi chuyn sang ch nhn v do

vy tit kim thi gian hn. Trnh ng dng c th iu lung theo c im ring ca mnh, khng

ph thuc vo phng thc iu ca h iu hnh. C th s dng lung mc ngi dng c trn nhng h iu hnh khng

h tr a lung bng cch b sung th vin lung m cc ng dng c th dng chung.

Nhc im: Khi mt lung ca tin trnh gi li gi h thng v b phong ta, th ton b

tin trnh s b phong ta v phi i cho ti khi li gi h thng thc hin xong.

Khng cho php tn dng kin trc nhiu CPU. Do h iu hnh phn phi CPU cho c tin trnh ch khng phi tng lung c th nn tt c cclung ca tin trnh phi chung nhau mt CPU thay v thc hin song song trn nhiu CPU khc nhau.

Lung mc nhn

Lung mc nhn c h iu hnh to ra v qun l. H iu hnh cung cp giao din lp trnh bao gm mt s li gi h thng m trnh ng dng c th gi yu cu to/xa lung v thay i tham s lin quan ti qun l lung. u im ch yu ca lung mc nhn l khc phc c cc nhc im ca lung mc ngi dng. Trn h thng vi nhiu CPU, lung mc nhn c th c cp CPU khc nhau thc hin song song.

Nhc im ch yu ca lung mc nhn so vi lung mc ngi dng l tc . Vic to v chuyn lung i hi thc hin trong ch nhn v do vy cn mt s thao tc chuyn t ch ngi dng sang ch nhn v ngc li.

IU TIN TRNHTiu ch ca iu tin trnh: Lng tin trnh c thc hin xong: s lng tin trnh thc hin xong trong mt n v thi gian.

Hiu sut s dng CPU. T l phn trm thi gian CPU trong trng thi hot ngThi gian vng i trung bnh tin trnh. thi gian t lc c yu cu khi to tin trnh ti khi tin trnh kt thc (tng thi gian ti tin trnh, thi gian ch i, chy, vo/ra d liu).Thi gian ch i. Tnh bng tng thi gian tin trnh nm trong trng thi sn sng v ch c cp CPU, ph thuc thut ton iu CPU.Thi gian p ng. y l tiu ch hng ti ngi dng v thng c s dng trong h thng tng tc trc tip: tiu ch quan trng l m bo thi gian t lc nhn c yu cu cho ti khi h thng c p ng.Ngoi ra cng cn quan tm n tnh cng bng v tnh d on c

Cc dng iu

iu di hn v ngn hnquyt nh thm vo danh

sch ang hot ng.

quyt nh cp b nh cho tin trnh

quyt nh cp CPU cho tin trnh thc hin.

iu c phn phi li l kiu iu s dng c ch ngt thu hi CPU ca mt tin trnh, phn phi li CPU mt cch ch ng, khng cn ch cho ti khi tin trnh ang chy kt thc hoc chuyn sang trng thi ch i.

iu khng phn phi li: Tin trnh ang trng thi chy s c s dng CPU cho n khi tin trnh kt thc, hoc chuyn sang trng thi ch i hoc li gi h thng, hoc ch i tn hiu ng b t tin trnh khc, cn gi l iu hp tc (cooperative)

a) iu c phn phi li v khng phn phi li (Preemptive - Nonpreemptive)

C ch iu

c quyn: Tin trnh ton quyn s dng processor cho n khi kt thc hoc t ng tr li Quyt nh iu khi tin trnh chuyn t

Running sang Waiting (blocked) hoc kt thc

Khng c quyn: Tin trnh ang x l th b thu hi processor cp cho tin trnh khc Quyt nh iu khi tin trnh chuyn t

Running sang Waiting (blocked) hoc ready hoc kt thc hoc t Waiting sang ready

Cc c im ca tin trnh

Tnh hng xut nhp

Tnh hng x l

Tng tc hay x l theo l

u tin ca tin trnh

Thi gian s dng CPU

Thi gian cn li tin trnh hon tt

T chc iu

HH s dng 2 loi danh sch t chc lu tr cc tin trnh:

Danh sch Ready: Ch tn ti 1 danh sch ny

Danh sch Waiting: C th tn ti nhiu danh sch ny

Cc chin lc iu

a) Chin lc FCFS: Tin trnh no c a vo danh sch ready trc s c cp Processor trc.

V d

Tin trnh Thi im vo

t/g x l

P1 0 24

P2 1 3

P3 2 3

Thi im cp processor

P1 P2 P3

0 24 27

Thi gian ch: P1: 0, P2: 23, P3: 25

Thi gian ch i trung bnh: Ttb = (0 + 24 + 27)/3

= 17

Nhn xt, nu cp CPU theo th t P2, P3, P1, hoc P3,

P2, P1, ta c: Ttb = (0 + 3 + 6)/3 = 3

b) Chin lc phn phi xoay vng: Round Robin (RR)

Tin trnh no vo danh sch Ready trc c cp processor trc

Mi tin trnh ch c s dng processor trong 1 khon thi gian bng nhau c gi l Quantum

V d Tin trnh Thi im vo t/g x lP1 0 24

P2 1 3

P3 2 3

Quantum=4

Tin trnh

P1 P2 P3 P1 P1 P1 P1

Thi im

0 4 7 10 14 18 22

Mt v d khc:

Vi

Quantum = 2,

c) Chin lc theo u tin: Mi tin trnh c gn mt u tin tng ng,

tin trnh c u tin cao nht s c cp pht CPU u tin

u tin ca tin trnh do HH gn v c th b thay i

Gii thut iu vi u tin c th theo nguyn tc c quyn hay khng c quyn

iu vi u tin v khng c quyn s thu hi processor t tin trnh hin hnh cp cho tin trnh mi nu u tin ca tin trnh ny cao hn

iu vi u tin v c quyn s ch chn tin trnh mi vo danh sch sn sng ti v tr ph hp.

Tin trnh u tin

t/g x l

P1 3 24

P2 2 3

P3 1 3

Thi im cp processor

P1 P2 P3

0 24 27

Nhc im: Tin trnh c u tin thp d ri vo trng thi ch v hn=>Cn gim u tin ca tin trnh sau mi ln c cp processor

V d

d) Chin lc cng vic ngn nht (shortest job first - SJF):

y l mt trng hp c bit ca gii thut iu vi u tin

u tin p c gn cho mi tin trnh l nghch o ca thi gian x l t m tin trnh yu cu : p = 1/t

CPU c s c cp pht cho tin trnh yu cu t thi gian nht kt thc tin trnh

Gii thut ny cng c th c quyn hoc khng c quyn

V d:

Thi gian ch i trung bnh

(6 + 2 +0)/3 = 2,67.

e) Chin lc nhiu cp u tin Phn lp cc tin trnh ty theo u tin ca

chng c cch thc iu thch hp cho tng nhm

Mi danh sch bao gm cc tin trnh c cng u tin v c p dng mt gii thut iu thch hp iu

Ngoi ra, cn c mt gii thut iu gia cc nhm, thng gii thut ny l gii thut khng c quyn v s dng u tin c nh

Mt tin trnh thuc v danh sch cp u tin i s ch c cp pht CPU khi cc danh sch cp u tin ln hn i trng

f) iu u tin thi gian cn li ngn nht (Shortest Remaining Time First SRTF)

Khi mt tin trnh mi xut hin, h iu hnh so snh thi gian cn li ca tin trnh ang chy vi thi gian tin trnh mi xut hin yu cu. Nu ngn hn, HH s thu hi CPU phn phi cho tin trnh mi. Vd:

g) iu vi nhiu hng il phng php iu trong tin trnh c phn chia thnh nhiu loi ty theo c im v u tin. Mi loi c xp trong mt hng i ring v c iu theo mt phng php ph hp vi c im ca loi tin trnh .Thng thng, tin trnh tng tc trc tip c iu theo phng php quay vng RR trong khi tin trnh nn c iu FCFS.

iu (scheduling) hay lp lch l quyt nh tin trnh no c s dng ti nguyn

phn cng khi no, trong thi gian bao lu. Bi ton iu c t ra vi mi dng ti nguyn khc nhau, chng hn thit b vo

ra, CPU, b nh, k c trong trng hp c chia s thi gian hay khng. iu tin

trnh ch yu tp trung vo thut cp pht CPU cho tin trnh.

IU TIN TRNH

TI NGUYN GNG V ON GNG

2.1 Ti nguyn gng(Critical Resource)

Ti nguyn gng?

Nhng ti nguyn c HH chia s cho nhiu tin trnh hot ng ng thi dng chung m c nguy c tranh chp gia cc tin trnh ny khi s dng chng

Ti nguyn gng c th l ti nguyn phn cng hoc phn mm, c th l ti nguyn phn chia c hoc khng phn chia c

2.1 Ti nguyn gng (Critical Resource)

V d: bi ton rt tin ngn hng t ti khon dng chung

If (ti khon tin rt >=0)

ti khon:=ti khon tin rt

Else

Thng bo li

endif

2.2 on gng (Critical Section)

Cc on code trong cc chng trnh dng truy cp n ti nguyn gng c gi l on gng

hn ch li c th xy ra do s dng ti nguyn gng, ti 1 thi im HH ch cho 1 tin trnh nm trong on gng

HH c c ch iu tin trnh qua on gng

Yu cu ca cng tc iu tin trnh qua on gng

Ti 1 thi im ch cho php 1 tin trnh nm trong on gng, cc tin trnh khc c nhu cu vo on gng phi ch

Tin trnh ch ngoi on gng khng c ngn cn cc tin trnh khc vo on gng

Khng c tin trnh no phi ch lu c vo on gng

nh thc cc tin trnh trong hng i to iu kin cho n vo on gng khi ti nguyn gng c gii phng

iu tin trnh qua on gng Gii thut PetersonGii thut Peterson c xut ban u cho bi ton ng b hai tin trnh. Gi s c hai tin trnh P0 v P1 thc hin ng thi vi mt ti nguyn chung v mt on gng chung. Mi tin trnh thc hin v hn v xen k gia on gng vi phn cn li ca tin trnh.Gii thut Peterson yu cu hai tin trnh trao i thng tin vi nhau qua hai bin chung.Bin th nht int turn xc nh n lt tin trnh no c vo on gng. Bin th hai bao gm hai c cho mi tin trnh bool flag[2], trong flag[i] = true nu tin trnh th i yu cu c vo on gng.

a. Gii php phn cng: Cm ngt Dng cp ch th STI (SeT-ting Interrupt) v CLI

(CLean Interrupt)

V d:

Procedure P(i: integer)

begin

repeat

CLI;

;STI;

;until .F.

end;

Dng ch th TSL (Test_and_set)

Function TestAndSetLock(Var i:integer):boolean

Begin

if i=0 then

begin

i:=1;

TestAndSetLock:=true

end;

else

TestAndSetLock:=false

End;

Procedure P(lock: integer);

begin

repeat

while (TestAndSetLock(lock)) do;

;

lock:=0

;

until .F.

end;

b. Gii php dng bin kha

- Dng bin kha chung

Procedure P(lock: integer);

begin

repeat

while lock=1 do;

Lock=1

;lock:=0

;until .F.

end;

- Dng bin kha ring

Var lock1, lock2: byte;

begin

lock1:=0; lock2:=1

p1: repeat

while lock2=1 do;

Lock1:=1

;lock1:=0

;until .F.

p2: repeat

while lock1=1 do;

Lock2:=1

;lock2:=0

;until .F.

end

C. Gii php c h tr bi HH v ngn ng lp trnh

Dng Semaphore(n bo)

Semaphore S l 1 bin nguyn, khi gn bng 1 gi tr khng m, l kh nng phc v ca ti nguyn gng tng ng vi n

ng vi S c 1 hng i F(s) lu cc tin trnh ang ch trn S

Thao tc Down gim S 1 n v, Up tng S 1 n v

Mi tin trnh trc khi vo on gng cn gi Down gim S v kim tra nu S>=0 th c vo on gng

Mi tin trnh khi ra khi on gng phi gi Up tng S ln 1 n v v ktra nu S

Procedure Down(S);

Begin

S:=S-1;

If s

Procedure Up(S);

Begin

S:=S+1;If s

3. TC NGHN V CHNG TC NGHN

Tc nghn S xung t v ti nguyn ca cc tin trnh hot ng ng

thi trong h thng

Tc nghn thng xy ra vi xung t ti nguyn khng phn

chia c, t xy ra vi ti nguyn phn chia c. Vd Hai tin trnh P v Q thc hin ng thi. Mi tin trnh cn s dng ng thi hai ti nguyn X v Y trong mt khongthi gian nht nh. Ti nguyn X v Y ch c kh nng phc v mt tin trnh ti mt thi im.

iu kin hnh thnh tc nghn

1. S dng ti nguyn khng th chia s2. Chim gi v yu cu ti nguyn3. Khng thu hi ti nguyn t tin trnh ang

chim gi chng4. i vng trnBn iu kin trn l cn v xy ra b tc. Cn lu rng iu kin 2 l h qu ca iu kin 4 v iu kin 3, tch ring thun li cho vic tm hiu c ch x l b tc.

3.3 Cc mc phng trnh tc nghn

1. Ngn nga

2. D bo v trnh tc nghn

3. Nhn bit v khc phc

Loi tr tng h: C th trnh loi tr tng h i vi nhng ti nguyn cho php nhiu tin trnh s dng mt lc v d cc file trong ch c. Tuy nhin, trn thc t lun lun tn ti ti nguyn khng c kh nng chia s ng thi nh vy v cn m bo loi tr tng h khi s dng chng. Do vy khng th ngn nga iu kin v loi tr tng h.

Gi v ch: C hai cch ngn nga iu kin ny.

Cch th nht l yu cu tin trnh phi nhn ton b ti nguyn cn thit trc khi thc hin tip, nu khng nhn , tin trnh b phong ta ch cho n khi c th nhn ti nguyn.

Cch th hai l tin trnh ch c yu cu ti nguyn nu tin trnh khng gi ti nguyn no khc

Khng c phn phi li iu kin ny c th ngn nga nh sau. Khi mt tin trnh yu cu ti nguyn nhng khng c do b cp pht, h iu hnh s thu hi li ton b ti nguyn tin trnh ang gi. Tin trnh ch c th thc hin tip sau khi ly c ti nguyn c cng vi ti nguyn mi yu cu. Mt cch thc hin khc l khi tin trnh yu cu ti nguyn, nu ti nguyn cn trng, ta cp pht ngay. Nu ti nguyn do tin trnh khc gi v tin trnh ny ang ch cp thm ti nguyn th thu hi li cp cho tin trnh yu cu.

Ch i vng trn Mt trong nhng cch ngn nga ch i vng trn l xc nh mt th t cho cc dng ti nguyn trong h thng v ch cho php tin trnh yu cu ti nguyn sao cho ti nguyn m tin trnh yu cu sau c th t ln hn ti nguyn m tin trnh yu cu trc.

Phng trnh b tc ging ngn nga b tc ch u nhm m bo b tc khng th xy ra (thc cht cng l ngn nga). Tuy nhin, phng trnh b tc cho php ba iu kin u xy ra v ch m bo sao cho trng thi b tc khng bao gi t ti.

Mi yu cu cp ti nguyn ca tin trnh s c xem xt v quyt nh ty theo tnh hnh c th, thay v tun theo mt quy tc chung nh trong trng hp ngn nga. lm c nh vy, h iu hnh yu cu tin trnh cung cp thng tin v vic s dng ti nguyn ca mnh v s dng thng tin ny khi cp pht. Dng thng tin n gin v hiu qu nht l s lng ti a ti nguyn tin trnh cn s dng

QUN L B NH

1. TNG QUANC th hnh dung b nh my tnh nh mt chui cc nh c nh a ch bt ut 0. n v nh a ch c th l t my (words) nhng thng l byte. Trong qu trnh thc hin tin trnh, CPU c cc lnh t b nh v thc hin cc lnh ny. Cc lnh c th c yu cu c, x l v ghi d liu ngc vo b nh. c th thc hin cc lnh v x l d liu, c d liu v lnh u phi c gn a ch. CPU s dng a ch xc nh lnh v d liu c th.

Qu trnh to v ti chng trnh vo b nh

a ch l gic v a ch vt lDo v tr tin trnh trong b nh c th thay i, cn phn bit hai loi a ch: a ch lgic v a ch vt l.

a ch lgic l a ch c gn cho cc lnh v d liu khng ph thuc vo v tr c th ca tin trnh trong b nh. Khi thc hin chng trnh, CPU nhn thy v s dng a ch lgic ny tr n cc phn khc nhau ca lnh, d liu. Ton b a ch c gn trong chng trnh to thnh khng giannh lgic ca chng trnh. a ch vt l l a ch chnh xc trong b nh ca my tnh v c phn cng qun l b nh t ln BUS a ch truy xut n nh tng nga ch lgic c nh x sang a vt l nh mt c ch phn cng gi l khi nh x b nh (MMU=Memory Mapping Unit).

1.1 V sao phi t chc, qun l b nh?

CPU ch c th trao i thng tin vi b nh chnh

Cc chng trnh mun c thc thi cn cnp vo b nh chnh, to lp tin trnh tng ng x l

Cc h thng a chng trn b nh chnh ngoiHH c th c nhiu tin trnh ang hot ng

Kch thc b nh chnh l hu hn nhng yu cub nh th v hn

1.1 V sao phi t chc, qun l b nh?

HH cn phi t chc qun l b nh mtcch hp l c th:

a bt k mt tin trnh no vo bnh khi c yu cu, cho d khi trn bnh khng cn khng gian trng

Bo v cc tin trnh ca h iu hnh vcc tin trnh trn b nh, trnh cc trnghp truy xut bt hp l xy ra.

1.2 Nhim v ca b phn qun l b nh

Ti nh v

Bo v b nh

Chia s b nh

T chc b nh logic

T chc b nh vt l

Ti nh v

Trong cc h thng a chng khng gianb nh chnh thng c chia s chonhiu tin trnh v yu cu b nh ca cctin trnh lun ln hn khng gian b nhvt l m tin trnh m h thng hin c

Cn thc hin c ch hon i (Swap):

Mt chng trnh ang hot ng trn b nhs b a ra a (swap-out) v s c avo li(swap-in) ti thi im thch hp

Ti nh v

Khi thc hin swap-in 1 chng trnh voli b nh HH phi nh v n ng vov tr m trc khi n b swap-out

HH phi c c ch ghi li tt c ccthng tin lin quan n 1 chng trnh bswap-out.

Cc thng tin ny l c s h iuhnh swap-in chng trnh vo li b nhchnh v cho n tip tc hot ng.

Bo v b nh

Mi tin trnh phi c bo v chng lis truy xut bt hp l v tnh hay c ch ca cc tin trnh khc.

Mi tin trnh ch c php truy xut nkhng gian a ch m HH cp cho n

B phn Ql b nh phi bit khng gian ach ca tt c cc tin trnh trn b nh

Khi tin trnh a ra a ch truy xut b phnQl b nh phi kim tra tt c cc yu cutruy xut b nh ca mi tin trnh

Chia s b nh

Bt k mt chin lc no c ci t u phi c tnh mm do cho php nhiu tin trnh c th truy cp n cng mt a ch trn b nh chnh

T chc b nh logic

B nh chnh ca h thng my tnh c t chc nh l mt dng hoc mt mng

Khng gian a ch bao gm mt dy c th t cc byte hoc cc word.

B nh ph cng c t chc tng t

Cch t chc ny c s kt hp cht ch vi phn cng my tnh nhng li khng ph hp vi cch xy dng ca chng trnh

i a s cc chng trnh c t chc thnh cc modul

T chc b nh vt l

B nh my tnh c t chc theo 2 cp: B nh chnh: tc truy xut nhanh,

nhng gi thnh cao v d liu khng th tn ti lu di trn n.

B nh ph: gi r, dung lng ln, d liu c lu tr lu di nhng tc truy xut chm.

Theo gin 2 cp ny, vic t chc lung thng tin gia b nh chnh v b nh ph l nhim v quan trng ca h thng

1.3 Khng gian a ch v khng gian vt l

a ch logic: cn gi l a ch o, l tt ccc a ch do b x l to ra.

a ch vt l: l a ch thc t m trnhqun l b nh nhn thy v thao tc.

Khng gian a ch: l tp hp tt c cca ch o pht sinh bi mt chng trnh.

Khng gian vt l: l tp hp tt c cca ch vt l tng ng vi cc a ch o

1.4 Cc cu trc chng trnh

Cu trc chng trnh tuyn tnh

Cu trc chng trnh ng

Cu trc chng trnh Overlay

Cu trc chng trnh phn trang

Cu trc chng trnh phn on

Cu trc chng trnh tuyn tnh

Tt c cc modun, th vin s dng trong chng trnh khi bin dch s c bin dch thnh 1 modun duy nht

Khi thc hin HH phi np ton b modun ny vo b nh

Cu trc chng trnh ny c tnh c lp cao v c tc thc thi cao

Lm lng ph b nh v kch thc chng trnh tng ln khi bin dch

Cu trc chng trnh ng

Chng trnh c vit di dng cc modun ring r

c bin dch thnh cc modun ring r, cc th vin chun ca HH v ca NNlp trnh khng c tch hp trong modun chnh ca chng trnh

Khi thc thi chng trnh ch 1 modun chnh c np vo b nh, cc modun khc khi cn s c np vo sau

Cu trc ny tit kim c khng gian nh nhng thc thi chp hn cu trc tuyn tnh


Chng trnh c bin dch thnh cc modun ring r

Cc modun chng trnh c chia thnh cc mc khc nhau: Mc 0: Cha modul gc dng np

chng trnh Mc 1: Chc cc modul c gi bi mc 0 Mc 2: Chc cc modul c gi bi mc 1 Mc i: Chc cc modul c gi bi mc i-1


Cc modun trong cng mt mc c th c kch thc khc nhau, kch thc ca modun ln nht trong lp c xem l kch thc ca mc

B nh dnh cho chng trnh cng c t chc thnh cc mc tng ng vi cc chng trnh

Khi thc hin chng trnh HH np s overlay ca chng trnh vo b nh sau np cc modun cn thit ban u vo b nh

HH da vo s overlay np cc modun khc nu cn

Cu trc chng trnh phn trang

Cc modun chng trnh c bin dch thnh 1 modun duy nht nhng sau c chia thnh cc phn c kch thc bng nhau c gi l cc trang

B nh phi c phn trang, tc chia thnh cc khng gian nh bng nhau gi l khung trang

HH phi xy dng b iu khin trang(PCT-page control table)

Cu trc chng trnh phn on

Chng trnh c bin dch thnh nhiu modun c lp, c gi l cc on

B nh phi c phn on, tc chia thnh cc khng gian c kch thc c th khng bng nhau tng ng vi kch thc ca cc an chng trnh

Khi thc hin chng trnh HH c th np tt c cc on hoc 1 vi on cn thit vo cc phn on nh lin tip hoc k lin tip

HH phi xy dng b iu khin on(SCT-Segment control table)

2. K THUT CP PHT B NH

2.1 K thut phn chng c nh

Khng gian a ch c chia thnh 2 vng c nh

Vng a ch thp dng cha HH

Vng cn li (tm gi l user program) cp cho cc tin trnh c np vo b nh chnh


Vi h thng n chng:

Vic qun l b nh n gin v vng nh user program ch cp cho 1 chng trnh

HH s dng 1 thanh ghi gii hn ghi a ch ranh gii gia HH v chng trnh ngi s dng

Khi chng trnh ngi s dng a ra a ch cn truy xut, HH s so snh vi gi tr gii hn c ghi trong thanh ghi gii hn

Nu nh hn gi tr gii hn th HH t chi vic truy sut

Ngc li, nu ln hn s cho php truy xut


Vi h thng a chng: Vng nh user program c chia n phn khng nht thit

phi bng nhau. Mi phn c c gi l 1 phn chng

Mi tin trnh c th c np vo 1 phn chng bt k nu kch thc ca n


(8M)

(8M)

(8M)

(8M)

(8M)

(8M)

(8M)

OS (8M)

2M

4M

6M

8M

8M

12M

16M

OS(8M)

phn chng kch thc bng nhau

phn chng kch thc khng bng nhau

Hnh 3.1 V d v phn chng c nh ca b nh 64MByte


C 2 kh khn vi vic dng phn chngc nh c kch thc bng nhau Th 1: Nu chng trnh c kch thc qu

ln so vi 1 kch thc ca phn chng, gii quyt vic ny th:

Ngi lp trnh phi thit k chng trnh theo cu trc overlay

Ch 1 phn cn thit ca chng trnh mi c np vo b nh lc np chng trnh. Khi cn mudun no m khng sn c trong b nh ngi s dng phi np n vo ng phn chng ca chng trnh v s ghi ln bt k chng trnh hoc d liu trong


Th 2: Khi kch thc ca chng trnh nh hn kch thc ca 1 phn chnghoc ln hn kch thc ca phn chng nhng khng phi l bi s ca kch thc phn chng.

iu ny gy ra s phn mnh ni vi, lng ph b nh


khc phc nhc im ny c th s dng phn chng c nh c kch thc khng bng nhau

C 2 la chn a tin trnh vo dng phn chng ny


La chn 1:

Mi phn chng c mt hng i tng ng

Khi 1 tin trnh cn c np vo b nh s a vo hng i ca phn chng c kch thc va cha n c a vo phn chng

Nhc im: C th c phn chng ang trng nhng li c nhiu tin trnh ang ch vo phn chng khc

OS

Tin trnhmi


La chn 2: Dng 1 hng i chung

cho tt c cc phn chng

Khi c tin trnh mun np vo b nh nhng cha c np s c a vo hng i

Khi c phn chng trng, HH s chn tin trnh c kch thc va a vo phn chng

Phng php ny gy kh khn trong vic la chn tin trnh np vo phn chng

OS

Tin trnhmi

2.2 K thut phn chng ng

Vng nh user program khng c phn chia trc

Khi c tin trnh np vo b nh HH cp cho n khng gian nh ng kch thc ca n

Khi tin trnh kt thc vng nh ca n s c thu hi HH cp cho tin trnh khc k c tin trnh mi c kch thc nh hn vng nh ca tin trnh gii phng gii phng


OS- 128k

Process1

64k

Process2

128k

Process3

32k

Process4

128k

Process5

120kProcess6

65k

1. Tin trnh 1,2,3,4 ln lt c np vo b nh2. Tin trnh 2 kt thc, vng nh c gii phng3. Tin trnh 5 c np vo vng nh ca tin trnh

2 va gii phng4. Tin trnh 6 yu cu c np vo b nh nhng

khng th v khng c vng nh trng ph hp np trong khi tng dung lng nh cn trng ln hn kch thc m tin trnh yu cu


Trong k thut phn chng ng, HH phi a ra cc c ch thch hp qun l cc khi nh cp pht hay cn trng trn b nh.

HH s dng 2 c ch: Bn bt v Danh sch lin kt.

Hai c ch HH u chia khng gian nh thnh cc n v cp pht c kch thc bng nhau, cc n v cp pht lin tip nhau to thnh 1 khi nh, HH cp pht cc khi nh ny cho cc tin trnh


C ch bn Bit: Mi n v cp pht c i din bi mt Bit trong bn bit. n v cp pht cn trng i din bng bit 0, ngc li i din bng bit 1

Bn bit


C ch danh sch lin kt:

Mi khi trn b nh c i din bi mt phn t trong danh sch lin kt

Mi phn t gm 3 trng chnh:

Trng u tin: cho bit khi nh cp pht (k hiu P) hay cn trng (k hiu H)

Trng th 2: cho bit th t ca n v cp pht u tin trong khi

Trng th 3: cho bit n v tng s n v cp pht trong khi


Khi c mt tin trnh cn c np vo b nh m b nh c nhiu hn mt khi nh trng c kch thc ln hn kch thc ca tin trnh , HH phi quyt nh chn mt khi nh ph hp np tin trnh sao cho vic la chn ny dn n vic s dng b nh chnh l hiu qu nht.

C 3 thut ton m HH s dng trong trng hp ny: Best-fit, First-fit, v Next-fit


Best-fit: chn khi nh c kch thc va ng bng kch thc ca tin trnh cn c np vo b nh.

First-fit: HH s bt u qut qua cc khi nh trng bt u t khi nh trng u tin trong b nh, v s chn khi nh trng u tin c kch thc ln np tin trnh.

Next-fit: tng t nh First-fit nhng y HH bt u qut t khi nh trng k sau khi nh va c cp pht v chn khi nh trng k tip ln np tin trnh

2.3 K thut phn trang n

B nh chnh c chia thnh cc phn bng nhau v c nh, c nh s bt u t 0 v c gi l cc khung trang

Khng gian a ch ca cc tin trnh cng c chia thnh cc phn c kch thc bng kch thc ca mt khung trang c gi l cc trang

Khi tin trnh np vo b nh th cc trang c np vo cc khung trang bt k cn trng c th khng lin tip nhau


HH s dng cc bng trang(PCT) theo di v tr cc trang ca tin trnh trn b nh. Mi tin trnh c bng trang ring


S phn mnh trong c ch ny?

Nu kch thc ca tin trnh khng phi l bi s ca kch thc 1 khung trang th s xy ra hin tng phn mnh ni vi

2.4 K thut phn on n

B nh chnh c chia thnh cc phn c nh c kch thc khng bng nhau, c nh s bt u t 0 c gi l cc phn on

Mi phn on bao gm s hiu phn on v kch thc ca n

Khng gian a ch ca cc tin trnh k c cc d liu lin quan cng c chia thnh cc on c kch thc khng nht thit phi bng nhau

2.4 K thut phn on n

Khi tin trnh c np vo b nh th tt c cc on ca n c np vo cc phn on cn trng trn b nh, cc phn on ny c th khng lin tc nhau

theo di cc on ca cc tin trnh khc nhau trn b nh HH s dng cc bng phn on (SCT), thng thng mi tin trnh c 1 bng phn on ring

2.4 K thut phn on n

Mi phn t t rong bng phn on ti thiu gm 2 trng

Trng th nht: cho bit a ch c s ca phn on m on chng trnh tng ng c np

Trng th 2: cho bit di ca phn on

2.4 K thut phn on n

Code

100k

Data

64k

Stack

150

base limit

64

0

64

164

228

356

478100

164 64

356 150

3. K THUT B NH O

3.1 Khi nim nh o

thc thi chng trnh c kch thc ln hn b nh vt l cp pht cho n

cn xy dng chng trnh theo cu trc Overlay

gy kh khn cho ngi lp trnh

khc phc kh khn cho ngi lp trnh, tng s dng b nh o ra i

K thut b nh o cho php x l mt tin trnh khng c np ton b vo b nh vt l

3.1 Khi nim nh o

B nh o m hnh ho b nh nh mt bng lu tr rt ln v ng nht, tch bit hn khi nim khng gian a ch v khng gian vt l

Ngi s dng ch nhn thy v lm vic trong khng gian a ch o, chuyn i sang khng gian vt l do h iu hnh thc hin vi s tr gip ca cc c ch phn cng

3.2 Ci t b nh o

C th ci t b nh o theo 2 k thut

Phn trang theo yu cu: S dng k thut phn trang kt hp vi k thut swap

Phn on theo yu cu: s dng k thut phn on kt hp vi k thut swap

3.2.1 Phn trang theo yu cu

S dng k thut phn trang kt hp vi k thut swap

Mt chng trnh c xem nh 1 tp hp cc trang thng tr trn b nh ngoi

Khi thc thi h thng khng np ton b chng trnh vo b nh trong m ch np nhng trang cn thit trong thi im hin ti

Mt trang ch c np vo b nh trong khi cn thit

3.2.1 Phn trang theo yu cu

Cn c c ch phn cng phn bit cc trang ang b nh trong v cc trang ang b nh ngoiT chc bng trang nh k thut phn trang

n nhng 1 phn t trong bng trang cha nhiu thng tin phc tp hn

Cn c 1 bit cho bit trang tng ng ca tin trnh c hay khng trong b nh chinh v 1 bit cho bit trang c b sa i hay khng so vi ln np gn nht

Hin tng li trang

Khi h thng truy xut ti 1 trang c nh du l bt hp l s lm pht sinh li trang, HH x l li trang nh sau:Bc 1: Kim tra truy xut n b nh l hp l hay bt hp l

- Nu truy xut bt hp l : kt thc tin trnh- Ngc li : n bc 2

Bc 2: Tm v tr cha trang mun truy xut trn a.Bc 3: Tm mt khung trang trng trong b nh chnh

- Nu tm thy: n bc 4- Ngc li, thc hin c ch swap out 1

trang thch hp trn b nh chnh sau cp nht bng trang tng ng ri n bc 4

Hin tng li trang

Bc 4:

- Chuyn trang mun truy xut t b nh ph vo b nh chnh ti khung trang xc nh c

- Cp nht ni dung bng trang tng ng.

- Ti kch hot tin trnh ngi s dng

Thay th trang

Khi cc khung y m cn np thm trangth phi thay th mt trang ang c trnkhung

Nu trang b thay th c thay i ni dung thcn phi a ra a

C cc phng php chn phn t thay th:

Optimal: Thay th trang s lu c s dng nht trongtng lai

FIFO: trang trong b nh lu nht s c chn thay th

LRU (Least Recently Used ): trang c chn thayth s l trang lu nht cha c truy xut

3.2.2 Phn on theo yu cu

B nh o bao gm cc on(segment) c kch thuc khng c nh

Khi np on vo b nh th h iuhnh tm khong trng np on

C bng on qun l cc on

3.2.3 Phn on kt hp phn trang

Kt hp cc u im ca phn on vphn trang

B nh o bao gm cc on

Trong mi on thc hin phn trang

QUN L FILE V A

1. CC KHI NIM C BN

File?

File hay cn gi l tp tin, l tp hp thng tin/d liu c t chc theo mt cu trc no .

Ni dung ca tp tin c th l chng trnh, d liu, vn bn,...

Mi tp tin c lu trn thit b lu tr u c t tn.

Mi h iu hnh c qui c t tn khc nhau, tn tp tin thng c 2 phn: phn tn (name) v phn m rng (extension).

Cc thuc tnh trn file

Tn (name)

nh danh (identifier)

Kiu (type)

V tr (location)

Kch thc (size)

Gi (time), ngy (date) v nh danh ngi dng (user identification)

Cc thng tin tp tin c lu tr trn cu trc th mc v c duy tr trn thit b

Cc thao tc trn file

To M ng Ghi c Di chuyn Xa Tm Ly thuc tnh i tn .V.v.

Cc kiu file

File thng: l file vn bn hay file nh phn cha thng tin ca ngi s dng

Th mc: l nhng file h thng dng lu gi cu trc ca h thng file

File c k t c bit: lin quan n Vo/Ra thng qua cc thit b Vo/Ra tun t nh mn hnh, my in,..

File khi: dng truy xut trn thit b a

Cu trc file

Cc h iu hnh thng h tr ba cu trc file thng dng l:

Khng c cu trc: file l mt dy tun t cc byte

C cu trc: File l mt dy cc mu tin c kch thc c nh

Cu trc cy: File gm mt cy ca nhng mu tin khng cn thit c cng chiu di, mi mu tin c mt trng kho gip vic tm kim nhanh hn

2. CC PHNG PHP TRUY XUT

Truy xut tun t

Truy xut trc tip

3. CU TRC TH MC

3.1 Cu trc th mc dng n cp

Mt th mc cho tt c cc tp tin

Th mc n cp c nhiu hn ch khi s lng tp tin tng. V tt c tp tin c cha trong cng th mc, chng phi c tn khc nhau.

3.2 Cu trc th mc dng hai cp

Mi ngi dng c 1 th mc ring

cc ngi dng khc nhau c th c cc tp tin vi cng mt tn

Cu trc ny c lp mt ngi dng t ngi dng khc.

3.3 Cu trc th mc dng cy

3.4 Cu trc th mc dng th khng cha

chu trnh

C chung nhau th mc con v cc file

3.5. Cu trc th mc dng th tng qut

4. CC PHNG PHP CI T

H THNG QUN L TP TIN

4.1 BNG DANH MC QUN L TH

MC, TP TIN

Lu tr cc thng tin lin quan n cc tp tin v cc th mc ang tn ti trn a(hoc thit b lu tr khc)

Bng danh mc gm nhiu entry, mi entry s lu thng tin v tn, thuc tnh, v tr lu tr,... ca mt tp tin hay th mc.

Khi c tp tin/th mc c to ra, HH s dng mt entry trong bng danh mc cha cc thng tin ca n

Khi mt tp tin/th mc xa khi a th HH s gii phng entry ca n trong bng danh mc

4.1 BNG DANH MC QUN L TH

MC, TP TIN

S lng entry trong bng danh mc c th c nh hoc khng c nh

Bng danh mc thng c lu tr ti mt khng gian c bit no trn a

Trong qu trnh hot ng bng danh mc thng c HH np t a vo b nh sn sng cho vic truy xut file ca HH sau ny

4.2 Bng phn phi vng nh

HH chia khng gian a thnh cc khi (block) c kch thc bng nhau

Ni dung file c chia thnh cc block bng nhau v bng kch thc block trn a tr block cui cng

Khi lu tp tin trn a HH cp va s block lu tr tp tin HH t chc bng phn phi vng nh

lu gi dy cc khi trn a cp pht cho tp tin hay th mc

4.3 Cc phng php cp pht vng nh

Cp pht lin tc: lu tr tp tin trn dy cc block lin tip


Cp pht theo danh sch lin kt: s dng danh sch

lin kt cc block qun l cc block cha file

Word u tin ca mi block a c s dng nh 1 con tr tr n block k tip

Kch thc ca block a ln hn kch thc block file 1 word


Cp pht theo danh sch lin kt s dung Index:

Tt c cc con tr lin kt cc block c lu vo 1 v tr gi l khi ch mc

Mi tp tin c khi ch mc ca chnh n, l 1 mng a ch block a lu tp tin

I-NODES

HH thit k 1 bng nh theo di cc block ca 1 file c gi l I-nodes

Mt I-nodes gm 2 phn:

Phn 1 cha cc thuc tnh tp tin

Phn 2 c chia ra lm 2 phn nh

Phn nh th nht gm 10 phn t, mi phn t cha a ch khi d liu ca tp tin

Phn t th 11 cha a ch gin tip cp 1 (single indirect)

Phn t th 12 cha a ch gin tip cp 2 (double indirect)

Phn t th 13 cha a ch gin tip cp 3 (double indirect)

I-NODES

a ch gin tip cp 1:Cha a ch ca mt khi,trong khi cha mtbng c th t 210 n 232phn t m mi phn tmi cha a ch ca khid liu ca tp tin

a ch gin tip cp 2:cha a ch ca bng cckhi a ch gin tip cp 1

a ch gin tip cp 3:cha a ch ca bng cckhi a ch gin tip cp2.

Ti liu tham kho

T Minh Phng: Gio trnh H iu hnh. Hc Vin CNBCVT, H Ni 2013

Trn Hnh Nhi, Gio trnh HH nng cao, H Khoa hc T nhin Tp.HCM, 1998

Nguyn Gia nh-Nguyn Kim Tun, Nguyn L HH, NXB Khoa hc k thut, 2005

William Stallting, Operating Systems, Prentice Hall, 1995

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