1 Nguyn l H iu Hnh Trnh by: Quc Huy B mn Khoa Hc My Tnh Khoa CNTT HBK HN 2 Nguyn l H iu Hnh Thi lng : 60 tit. V tr mn hc : sau Tin Hc i Cng Mc ch mn hc: trang b kin thc v h iu hnh, khai thc h thng hiu qu hn.3 Ti liu tham kho Ting Anh: Operating System Concept and Design Milan Milenkovic Modern Operating System Adrew S. Tanenbaum Ting Vit: Bi ging h iu hnh Nguyn Thanh Tng Lp trnh hp ng v my vi tnh IBM PC- Peter Norton Cm nang Lp trnh h thng Micheal Tischer 4 Ni dung mn hc Chng 1: Cc khi nim c s Chng 2: Qun l tin trnh Chng 3: Qun l Processor Chng 4: Qun l b nh Chng 5: Qun l thit b ngoi vi v file Chng 6: H thng nhiu Processors Chng 7: virus my tnh Chng 8: Tng quan v cc loi h iu hnh5 Chng 1: Cc khi nim c bn v h iu hnh Bi 1: Cu trc phn lp ca h thng tnh ton Bi 2: nh ngha v phn loi h iu hnh Bi 3: Cc tnh cht v nguyn tc xy dng h iu hnh Bi 4: Mt s hnh thi giao tip ngi - my 6 Bi 1: Cu trc phn lp ca h thng tnh ton 1.H thng tnh ton gm : mi trng ca h thng v ngi s dng. Platform, gm c: phn cng my tnh , phn mm my tnh Phn cng: - my tnh - kt ni my tnh - truyn thng my tnh 7 1.1 Phn cng my tnh Kin trc chung ca my tnh My tnh gm nhng thnh phn ? -B vo ra-B nh- B vi x l - ng truyn 8 B vo ra B vo ra lm nhim v nhn d liu, cc thng tin vo t cc vt mang tin nh a t, bn phm.., chuyn n b nh qua ng truyn di s iu khin ca b x l, ngc li chuyn thng tin t b nh qua ng truyn ti cc vt mang tin, qu trnh ny cng chu s iu khin ca b nh. 9 B nh lu tr thng tin trong qu trnh my tnh x l 2 dng lu tr: Tm thi RAM (Random Access Memory): B nh truy xut ngu nhin lu tr d liu v chng trnh trong qu trnh thao tc v tnh ton Bn vng ROM (Read Only Memory): B nh ch c thng tin lu tr cc chng trnh h thng, chng trnh iu khin vic nhp xut c s10 B nh Nguyn tc Voneuman B nh my tnh gm nhiu ngn nh c nh a ch. Khi x l th theo a ch ch khng x l theo ni dung 11 B x l Central Processor Unit (CPU) Thc hin 2 cng vic: iu khin hot ng ca cc thit bkhc Ch bin thng tin Gm cc thnh phn: Khi iu khin (Control Unit - CU) Khi tnh ton s hc v logic (Arithmetic Logic Unit ALU) Cc thanh ghi (Register) Cc ng truyn thng tin (internal bus) B nh tng tc Cache 12 1.2 Kt ni my tnh My tnh c kt ni vi h thng khc tng hiu nng s dng Vd: My tnh kt ni vi my tnh -> mng my tnh. m bo truyn thng: s dng cc giao thc (protocol) Mng my tnh phn loi thnh: LAN (Local Area Network) WAN (Wide Area Network) GAN (Global Area Network) Internet 13 1.3 Truyn thng my tnh Tn hiu tng t (Analog Signal) Truyn lin tc Ch truyn c trn mt ng truyn Chm, d b nhiu Khi b ngt s phi truyn li t u Tn hiu s (Digital Signal) Thng tin c s ha ng gi thnh cc gi tin (packet) C th truyn song song trn nhiu ng truyn M ha, bo mt 14 2. Phn mm Software: l cc phng thc hay cch thc iu khin phn cng. nh ngha: l mt h thng cc chng trnh cho php khai thc v m rng kh nng ca my tnh. 15 Phn loi phn mm Tiu ch thng mi Publicware: l nhng phn mm s dng ph bin trong cng ng Shareware:l phn mm c php dng th trong mt gii hn no Licence ware: bt buc phi mua v ng k bn quyn Freeware: t do sao chp, sa i Tiu ch pht trin phn mm Phn mm ngun ng Phn mm m ngun m 16 Phn loi phn mm Kin trc ng dng ngi dng (User Application) ng dng h thng (System Application) H iu hnh BIOS 17 3. Ngi s dng Chia lm 3 lp: Lp trnh vin (Programmer) Ngi s dng cui cng (end-user) Thao tc vin (Operator) 18 4. Ti nguyn ca h thngtnh ton Bao gm: Tt c cc ngoi vi B nh B x l Cc chng trnh ca h thng 19 4. Ti nguyn ca h thngtnh ton Chia thnh 2 loi c bn: Ti nguyn hu hn kh nng phc v VD: Ti nguyn v hn kh nng phc v VD: 20 Bi 2. nh ngha v phn loih iu hnh 1. Mt vi nh ngha h iu hnh T quan im ca ngi s dng:H iu hnh l tp hp cc chng trnh, phc v khai thc h thng tnh ton mt cch d dng, thun tin T quan im ca ngi qun l: H iu hnh l mt tp cc chng trnh phc v qun l cht ch v s dng ti u cc ti nguyn ca h thng tnh ton 21 Mt vi nh ngha h iu hnh nh ngha t quan im cn b k thut: H iu hnh l h thng chng trnh, trang b cho mt my tnh c th to ra mt my logic mi vi cc ti nguyn v kh nng mi. nh ngha t quan im k s lp trnh h thng: H iu hnh l h thng m hnh ha, m phng cc hot ng ca my, ca ngi s dng v ca thao tc vin, hot ng trong ch i thoi, nhm to mi trng khai thc thun tin v qun l ti u cc ti nguyn ca h thng tnh ton 22 2. Phn loi h iu hnh H iu hnh n mc ch, a mc ch H iu hnh n mc ch: ch phc v cho mt chc nng duy nht trn my tnh, gii quyt bi ton xc nh. H iu hnh a mc ch: mt thi im cho php thc hin mt chng trnh phc v nhiu yu cu khc nhau 23 2. Phn loi h iu hnh H iu hnh tp trung v phn tn HH tp trung : trong h thng my tnh ch c mt h iu hnh duy nht ci t vo my ch, h iu hnh ny c chc nng khi ng v cung cp dch v cho cc my tnh khc. Cc my ny ch yu vo ra cc d liu. Vic x l tp trung vo my ch. HH phn tn: Trong h thng my tnh, mi my c h iu hnh ringkhi ng c lp v c chc nng khc nhau. H iu hnh ti my ch c gi l h iu hnh phn tn v: Qun l cc ti nguyn h thng khng ch ti my ch m cn c cc my trm trong h thng. Cha s ti nguyeen ng thi cho nhiu my khc nhau. 24 2. Phn loi h iu hnh H iu hnh phn chia thi gian v h iu hnh thi gian thc. H iu hnh phn chia thi gian (Sharing time) : mt b x l nhng thi im khc nhau phc v cho chng trnh khc nhau hay ni khc i thi gian x l ny b chia s cho nhiu chng trnh do vy tn ti cc khong thi gian c nhng chng trnh b ri vo trng thi ch i hay trng thi khng c phc v. H iu hnh thi gian thc : cc thi im lin tc trong h thng chng trnh lun c phc v bi mt CPU v c th l nhng thi im khc nhau, mt chng trnh s c phc v bi c b x l khc nhau. 25 3. Lch s pht trin cch iu hnh Th h 1 (1943-1955) Th h 2 (1955-1965) Th h 3 (1965-1980) Th h 4 (1980 n nay) 26 Th h 1 (1943-1955) Howard Aiken Havard v John von Neuman Princeton xy dng thnh cng my tnh Dng cc ng chn khng vi hn 10000 ng Lp trnh: thit lp cc cng tc Ngn ng lp trnh: ngn ng my Tc chm i thit k my cng l i lp trnh i ch to my Qun tr h thng Thao tc h thng 27 A Famous Remark (1943) "I think there is a world market for maybe five computers."Thomas Watson, chairman of IBM 28 Th h 2 (1955-1965) Thit b bn dn ra i ( Transistors) Lp trnh: trn phiu c l Ngn ng lp trnh: FORTRAN & Assembly Cng vic: mang tnh khoa hc My tnh: Mainframes H iu hnh: X l theo l Batch system Cc trng i hc bt u mua my tnh(gi my ln n hng triu $) C s phn chia gia ngi thit k, ngi ch to, ngi vn hnh, ngi lp trnh v chuyn vin bo tr. 29 Punched Card 30 H thng x l theo l - Mang phiu n my IBM 1401 (good at card reading) - c ni dung phiu ra bng t - Cho bng t vo my IBM 7094 thc hin tnh ton - Cho bng t vo my IBM 1401 in kt qu xut ra ngoi 31 A Famous Remark (1957) "I have traveled the length and breadth of this country and talked with the best people, and I can assure you that data processing is a fad that won't last out the year. The editor in charge of business books for Prentice Hall 32 Th h 3 (1965-1980) My tnh s dng cc mch tch hp (Integrated Circuit IC) Lp trnh: Bng t Ngn ng lp trnh: FORTRAN & Assembly Cng vic: khoa hc v thng mi My tnh: IBM 360, DEC PDPs H iu hnh: Multiprogramming/timesharing, spooling Chng trnh h iu hnh di c triu dng hp ng v do hng ngn lp trnh vin thc hin Cc h iu hnh pht trin: MULTICS (cha ca cc h iu hnh hin i) UNIX (System V, BSD) POSIX (bi IEEE) MINIX (bi Tanenbaum) Linux (derived from MINIX 33 A Famous Remark (1977) There is no reason anyone would want a computer in their home. Ken Olson, president, chairman and founder of Digital Equipment Corp. 34 Th h 4 1980 n nay S dng cng ngh Very large scale instruction - VLSI Lp trnh: bc cao Ngn ng lp trnh: C/C++, Java, My tnh: PC H iu hnh: Windows, MacOS, Linux 35 Bi 3. Tnh cht v nguyn tc xy dng h iu hnh 1. Tnh cht chung ca h iu hnh: A) Tin cy v chun xc B) An ton cao C) K tha v thch nghi D) Hiu qu E) Thun tin 36 Tin cy Mi cng vic trong h thng u phi c kim tra: Kim tra mi trng iu kin thc hin, Kim tra kt qu thc hin, Nhiu chc nng KT: chuyn giao cho phn cng. V d: Lnh COPY A:F1.TXT B: Sau khi KT c php, bt u thc hin lnh. Ln lt h thng s KT g v c th c thng bo no? 37 Kt CARD I/O, Tn ti a? Thit b in t a? ng c a? Kh nng truy nhp ca a? Kh nng truy nhp a? Tn ti file F1.TXT? Kh nng truy nhp file? . . . . . . . . 38 An ton cao Hn ch truy nhp khng hp thc, Hn ch nh hng sai st v tnh hay c , Bo v: Nhiu mc, Nhiu cng c, Nhiu thi im v giai on khc nhau. 39 K tha v thch nghi tThi im to OSK thaThch nghi40 i vi vic nng cp, tnh k tha l bt buc Cc thao tc, thng bo phi khng c thay i, nu c th khng ng k v phi c hng dn c th. m bo tnh tha k s duy tr v pht trin i ng ngi s dng41 Hiu qu cao Ti nguyn h thng phi c khai thc trit m bo duy tr hot ng ca ton h thng42 Thun tin H thng phi d dng s dng C nhiu mc hiu qu khc nhau H thng tr gip phi phong ph, a dng Tra cu, hng dn, tooltip 43 2.NGUYN L T CHC V HOT NG Nguyn l m un, Nguyn l ph chc nng, Nguyn l Macroprocessor, Nguyn l bng tham s iu khin, Nguyn l gi tr chun, Nguyn l 2 loi tham s. 44 NGUYN L M UN M un :cc n v chng trnh, chng trnh con, lp (class), i tng (object)... Mi m un phi c tnh cht: c lp tng i v mt chc nng M0I0I1O0M1I2O1M2I3O245 NGUYN L M UN Mi cng vic m un CT c lp, Cc m un lin kt vi nhau thng qua Input/Output: Cc m un c nhm theo chc nng thnh phn h thng. M0I0I1O0M1I2O1M2I3O246 NGUYN L PH CHC NNG Mi cng vic trong h thng thng thng c th thc hin bng nhiu cch vi nhiu cng c khc nhau, L do: Mi m un c hiu ng ph chc nng, Ngi dng c quyn khai thc mi hiu ng ph khng ph thuc vo vic cng b, Vai tr: m bo thun tin cho ngi dng, m bo an ton chc nng ca h thng, V d: In mt file. 47 NGUYN L MACROPROSSECOR Trong OS khng c sn chng trnhgii quyt vn Khi cn thit: H thng to ra CT v thc hin CT to ra: Nguyn l ny p dng vi c bn thn ton b OS: Trn a ch c cc thnh phn. Khi cn cc thnh phn c lp rp thnh H IU HNH (Np h thng). Vn Lp trnh Thc hinKt quMacroprocessor48 NGUYN L MACROPROSSECOR Mi h iu hnh u s dng nguyn l ny trong i thoi ngi- my trn ngn ng vn hnh. su trong phn tch c php ca cc h thng l khc nhau c p dng rng ri trong cc h c s d liu49 NGUYN L BNG THAM S IU KHIN Mi i tng trong OS Bng tham s (Control Table, Control Block), H thng khng bao gi tham chiu ti i tng vt l m ch tham chiu ti bng tham s iu khin tng ng. Vi cc a t, CD bng tham s ghi phn u Vng h thng (System Area), Vi cc files Header. 50 Cu trc file nh kiu HeaderCc bn ghiGii m headerCc trng ca headerGii m bn ghi51 Mt s loi bng tham s : Cho WINDOWS: Win.ini, Cho MS DOS: Config.sys, Cho WINWORD: Winword.ini, Bng tham s cu hnh h thng: phc v cho mi h iu hnh: lu tr trong CMOS, 52 NGUYN L GI TR CHUN Cch gi khc: Nguyn tc ngm nh (Default), H thng chun b bng gi tr cho cc tham s - bng gi tr chun, Khi hot ng: nu tham s thiu gi tr OS ly t bng gi tr chun. Vai tr ca nguyn l: Thun tin: khng phi nhc li nhng gi tr thng dng, Ngi dng khng cn bit y d hoc su v h thng. 53 Nguyn l gi tr chun Tc ng ln gi tr tham s hoc bng gi tr chun: Startup, Autoexec.bat, Control Panel V d: c:\csdl>dir Tham s thiu gi tr: a? Th mc? Xem g? Quy cch a ra? Ni ra? 54 NGUYN L 2 LOI THAM S 2 loi tham s: Tham s v tr (Position Parameters), Tham s kho (Keyword Param.). Tham s kho theo trnh t tu . C:\CSDL\DIR A:\ /S /P /ON /L /WTham s v trTham s kho55 Nguyn tc bo v nhiu mc Mi ti nguyn c c trng vt l khc nhau -> phng php v mc bo v, cch thc bo v khc nhau -> xy dng nhiu lp bo v an xen, h tr ln nhau mi c th ngn chn cc s can thip tri php vo ti sn h thng. VD: Hng ro an ninh mng 56 Nguyn l khi to khi ci t (nguyn l sinh generate) sinh ra (khi to) mt h thng trc ht phi la chn cc m un chng trnh t kho m un sn c sao cho p ng c cc yu cu ngi dng, ph hp cu hnh k thut ca my T chc lu tr v gn kt cc m un chn to thnh h thng mong mun Do phn mm Setup thc hin 57 3.Thnh phn ca h iu hnh Thnh phn ca h thng iu khin Thnh phn ca h thng phc v 58 4.Kin trc phn lp Giao tip ngi -my Kernel User mode Kernel iu phi BIOS Gc ngi s dng 59 4.Kin trc phn lp Giao tip ngi myQun l ti nguyn Qun l thit b DRIVER BIOS Gc ngi lp trnh h thng 60 Kin trc h iu hnh DOS 61 Kin trc Unix 62 Kin trc phn lp ca THE 63 5.Cc dch v ca h iu hnh Thi hnh chng trnh : h thng phi c kh nng np chng trnh vo b nh v thi hnh n. Chng trnh phi chm dt thi hnh theo cch thng thng hay bt thng (c li). Thao tc nhp xut : Mt chng trnh thi hnh c th yu cu nhp xut. Nhp xut ny c th l tp tin hay thit b. i vi thit b c mt hm c bit c thi hnh. tng hiu qu, ngi s dng khng truy xut trc tip cc thit b nhp xut m thng qua cch thc do h iu hnh cung cp.64 Cc dch v ca h iu hnh Thao tc trn h thng tp tin Thng tin : Thng tin c th c ci t qua chia x b nh, hoc bng k thut chuyn thng ip. Pht hin li : h iu hnh phi c kh nng bo li. Li xy ra c th do CPU, b nh, trong thit b nhp xut, hay trong cc chng trnh. i vi mi dng li, h iu hnh s c cch gii quyt tng ng65 6.Li gi h thng System calls cung cp mt giao tip gia tin trnh v h iu hnh. Mt s h thng cho php li gi h thng c thc hin t cp lp trnh ngn ng cp cao, nh cc hm v li gi hm. N c th pht sinh li gi t cc th tc hay gi trc tip inline66 Bi 4. Mt s hnh thi giao tip ngi - my Dng lnh (Command line) Bng chn (Menu) Biu tng (Icon) 67 1.Dng lnh Khi nim:Theo nguyn l macro, thun tin cho ngi dng trong h iu hnh xy dng b Macro tng ng vi cc chc nng ca HH. Mi macro c quy cch: Tn Macro ton hng v tham s VD: DIRC:\ *.* / P Tn ca macro c tnh gi nh. 68 Dng lnh (tip) Nguyn tc xy dng: xy dng mt h thng macro trong giao tip gia ngi s dng vi my tnh, cc macro ny c phn cp thnh cc nhm ng dng69 u nhc im - n gin nhng c t chc - Khng i hi cu hnh my phc tp - Vic gn thng s vo chng trnh l ht sc n gin. Hn ch: - Tc a lnh vo chm so vi cc hnh thi khc. - Ngi s dng phi nh tp lnh cng knh. - Khng thun tin cho ngi s dng hn ch v ngn ng giao tip70 2. Bng chn - Menu: bng chn 1 mc, mi mc chn (pad), cc mc chn c th sp t ty tin trn ca s. chn c th dng + Cc thit b tr: con chut, bt t, tay (i hi phi c mn hnh cm ng). + Phm tt (hotkey) : gn vi mi chcnng + phm dch chuyn: tri, phi v enter 71 2. Bng chn - Popup:l mt hp chn, mi mc chn gi l 1 bar (thanh), cc bar c th t . chn c th dng + Cc thit b tr: con chut, bt t, tay (i hi phi c mn hnh cm ng). + Phm tt (hotkey) : gn vi mi chcnng + phm dch chuyn: ln, xung v enter - Menu_Popup Kt hp gia Menu vi popup. 72 Nguyn tc xy dng: s dng k thut phn tch t trn xung, chia nh chc nng ri nhm cc chc nng. Qu trnh chia nh dng li khi nhn c chc nng mc n gin nht, khi ta xy dng mc 1 ng vi menu. Mi nhm con mc 2 tr xung th ta gn vi 1 popup 73 nh gi: u im : Khng i hi cu hnh my phc tp, khng phi nh tp lnh. Tc a lnh vo nhanh hn. Hn ch: Vn cha thun tin vi nhng ngi hn ch v ngn ng giao tip. Khng gn c tham s trc tip cho tr-ng trnh phi quay tr li ch dng lnh. 74 3) Biu tng Icon Gm nh km theo li ch: Anh: c trng cho chc nng V d Desktop (bn lm vic) : mn hnh lu biu t-ng cc chc nng thng dng nht 75 3) Biu tng Ca s: cc c trng thanh tiu , gc ca s bao gi c cng c nt iu khin, 2 thanh cun dch chuyn ni dung trong ca s. Ca s cho php zoom, di chuyn c trn mn hnh (float). Mu (mu nn, mu k t, mu bin); v tr ca s (ta cc nh x1,y1 v x2,y2) Ca s l mt vng lm vic, tng ng vi mt hay mt nhm cc chc nng. Khi ca s tng ng vi 1 chc nng th ca s cha cc biu tng. Ti mt thi im c th chn nhiu chc nng (m nhiu ca s trn mn hnh). Cc ca s c th trnh by theo 3 cch (Xp ngi/ gi nhau; chng (overlap), dn tri (title)). 76 Nguyn tc t chc Tng t bng chn 77 nh gi u: + Khng phi nh lnh + Thn thin d s dng + Nhp lnh nhanh + Chn nhiu lnh ng thi Nhc: + i hi cu hnh my cao (b nh ln, card mn hnh, tc my cao, cng dung ln ln) + Khng gn trc tiptham s cho chng trnh 78 Chng 2: Qun l tin trnh Bi 1. nh ngha v phn loi tin trnh Bi 2. Cc k thut iu Bi 3. Tc nghn (Deadlock) 79 Bi 1. nh ngha vphn loi tin trnh 1.nh ngha tin trnh Trng thi ca mt h thng tnh ton ti mt thi im c hiu l mt b thng tin ca tt c cc thnh phn trong h thng tnh ton. Mt dy chuyn trng thi ca h thng tnh ton k hiu l S0, S1,..Sn trong S0 l trng thi u, Sn l trng thi kt thc th ta gi l mt tin trnh.80 1.nh ngha tin trnh S0S1S2S3S4S5. . . . Sn-1SnSn+1. . . .ABVic chuyn trng thi h thng tnh ton phi da vo mt s kin pht sinh trong h thng gi l hintng ngt. 81 Tin trnh l mt chng trnh ang x l, s hu mt 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 CPU, b nh chnh, cc tp tin v thit b nhp/xut.82 Phn bit khi nim chng trnh v tin trnh Mt chng trnh l mt thc th th ng, cha ng cc ch th iu khin my tnh tin hnh mt tc v no . Khi cho thc hin cc ch th ny, chng trnh chuyn thnh tin trnh, l mt thc th hot ng, vi con tr lnh xc nh ch th k tip s thi hnh, km theo tp cc ti nguyn phc v cho hot ng ca tin trnh.83 Cc trng thi ca tin trnh Trng thi ca tin trnh ti mt thi im c xc nh bi hot ng hin thi ca tin trnh ti thi im . nguyn nhn mt tin trnh thay i trng thi : phi ch mt s kin no xy ra i mt thao tc nhp/xut hon tt buc phi dng hot ng do ht thi gian x l 84 Cc trng thi ca tin trnh Mi to : tin trnh ang c to lp.Running : cc ch th ca tin trnh ang c x l.Blocked : tin trnh ch c cp pht mt ti nguyn, hay ch mt s kin xy ra . Ready : tin trnh ch c cp pht CPU x l. Kt thc : tin trnh hon tt x l. Ti mt thi im, ch c mt tin trnh c th nhn trng thi running trn mt b x l bt k. Trong khi , nhiu tin trnh c th trng thi blocked hay ready85 Cu trc d liu khi qun ltin trnh Process Control Block (PCB) 86 Cu trc d liu khi qun ltin trnh nh danh ca tin trnh (1) : gip phn bit cc tin trnh Trng thi tin trnh (2): xc nh hot ng hin hnh ca tin trnh. Ng cnh ca tin trnh (3): m t cc ti nguyn tin trnh ang trong qu trnh, hoc phc v cho hot ng hin ti, hoc lm c s phc hi hot ng cho tin trnh, bao gm cc thng tin v: Trng thi CPU: ni dung cc thanh ghi, quan trng nht l con tr lnh IP lu tr a ch cu lnh k tip tin trnh s x l. Cc thng tin ny cn c lu tr khi xy ra mt ngt, nhm c th cho php phc hi hot ng ca tin trnh ng nh trc khi b ngt. 87 Ng cnh ca tin trnh (3) B x l: dng cho my c cu hnh nhiu CPU, xc nh s hiu CPU m tin trnh ang s dng. B nh chnh: danh sch cc khi nh c cp cho tin trnh. Ti nguyn s dng: danh sch cc ti mguyn h thng m tin trnh ang s dng. Ti nguyn to lp: danh sch cc ti nguyn c tin trnh to lp. 88 Cu trc d liu khi qun ltin trnh Thng tin giao tip (4): phn nh cc thng tin v quan h ca tin trnh vi cc tin trnh khc trong h thng : Tin trnh cha: tin trnh to lp tin trnh ny . Tin trnh con: cc tin trnh do tin trnh ny to lp . u tin : gip b iu phi c thng tin la chn tin trnh c cp CPU. Thng tin thng k (5): thng k v hot ng ca tin trnh thi gian s dng CPU, thi gian ch. Cc thng tin ny c th c ch cho cng vic nh gi tnh hnh h thng v d on cc tnh hung tng lai. 89 Process Control Block Process table H iu hnh lu con tr ti tng PCB ca mi tin trnh trong mt bng tin trnh ca ton h thng hoc tng ngi dng. Truy cp nhanh ti cc PCB Khi mt tin trnh b dng, h iu hnh loi b tin trnh khi bng tin trnh v gii phng tt c cc ti nguyn ca tin trnh 90 3. Process Control Block Process table 91 Thao tc trn tin trnh to lp tin trnh (create) kt thc tin trnh (destroy) tm dng tin trnh (suspend) ti kch hot tin trnh (resume) thay i u tin tin trnh 92 2 - Phn loi tin trnh Tin trnh k tip- Hai tin trnh c gi l k tip nu thi im bt u ca tin tnh ny l sau thi im kt thc ca tin trnh khc. 93 2 - Phn loi tin trnh Tin trnh song song: Hai tin trnh c gi l song song nu thi im bt u ca tin tnh ny nm gia thi im bt u v kt thc ca tin trnh khc. BEGINENDtBeginAB94 3 Phn loi tin trnh song songABCZabczABCZabczIIABCZbczABCZabczc lpQuan h thng tinPhn cpng mc95 Song song c lp Trong qu trnh hot ng khng trao i thng tin vi nhau v khng dng chung ti nguyn. Vic t chc tin trnh song song c lp ch yu l bo v thng tin, tin trnh ny khng xm phm n d liu v chng trnh ca tin trnh khc96 Song song khng c lp 2 tin trnh c trao i thng tin vi nhau Hai tin trnh c th trao i thng bo vi nhau. Mt tin trnh c th gi thng bo cho tin trnh khc. Trong mt s trng hp tin trnh nhn thng bo phi tr li. trao i thng tin gia cc tin trnh h thng t chc cc vng nh chung lm hm th. Mi tin trnh khi cn nhn thng bo c th kim tra ni dung hm th xem c thng bo hay khng v nu c th dnh cho tin trnh no. Cc tin trnh c th trao i thng tin vi nhau thng qua cc cng c cp cao qua cc tin trnh iu khin ca h thng, thng thng l qua chong trnh gim st (monitor). Cng c trao i cp cao cho php ch ng gi thng tin n tin trnh nhn vo ng thi im cn thit97 Song song c chia s ti nguyndng chung Trong qu trnh hot ng mt tin trnh c th khi to mt tin trnh khc hot ng song song. Tin trnh khi to l tin trnh chnh, tin trnh c khi to l tin trnh con. C hai m hnh phn phi ti nguyn : M hnh qun l ti nguyn tp trung : ti nguyn c phn phi trc tip cho c tin trnh chnh v tin trnh con.98 Song song c chia s ti nguyndng chung M hnh qun l ti nguyn phn tn. Ti nguyn c phn phi cho tin trnh chnh, tin trnh con nhn ti nguyn t tin trnh chnh. Cch phn phi ti nguyn ny n gin nhng khng ti u v ti nguyn phi c phn phi t sm. Trong bt k trng hp no, tin trnh con nhn ti nguyn u th phi tr v ni nhn . Do tin trnh chnh phi kt thc sau tin trnh con. Nu tin trnh con cha kt thc th dng cc lnh nh WAIT, POST tm ngng tin trnh chnh, ch tin trnh con kt thc, nhn li ti nguyn v tr cho h iu hnh. 99 Song song ng mc hai tin trnh lun phin s dng mt ti nguyn. Sau khi s dng xong ti nguyn chung, mt tin trnh bn giao li ti nguyn ny cho tin trnh khc. Bn thn tin trnh bn giao ti nguyn vn c th tip tc cc cng vic ring ca mnh trong thi gian ch nhn li ti nguyn chung. VD : for i :=1 to 10 do write(i) ; 100 BIU DIN TIN TRNHSONG SONG Gi thit: S1, S2, . . ., Sn cc cng vic thc hin song song (Trn 1 hoc nhiu my). S1S2Sn. . . .101 BIU DIN 2 cch m t ph bin: PARBEGINCOBEGIN S1 ; S1 ; S2;S2;

. . . . . . .. . . . . . . SnSn PAREND;COEND; Cc cng vic Si c m t chnh xc bng mt ngn ng lp trnh c th. 102 3. Ti nguyn gng Trong cc loi ti nguyn ca h thng tnh ton, da vo c im v nguyn l hot ng, c nhng ti nguyn c xem l v hn, hu hn ti nguyn phc v. VD : my in c coi l hu hn ti nguyn phc v.103 Ti nguyn gng Nu mt thi im no , 1 ti nguyn hu hn kh nng phc v li c nhiu tin trnh truy cp n th thi im ny, ta ni rng ti nguyn trng thi gng. Mt dy cc thi im gng k tip nhau to thnh on gng. Trong khong thi gian tin trnh s dng ti nguyn gng th ta gi l tin trnh gng. mt tin trnh c th chia lm 2 on : on gng v on cn li. 104 105 4. iu tin trnh m bo cc tin tnh qua on gng mt cch hp l nht. Ti mt thi im khng c qu 1 tin trnh vo on gng. khng tin trnh no chim on gng trong thi gian v hn. Khng c tin trnh no phi ch v hn trc khi vo on gng C 2 mc iu s cp v cao cp. 106 iu tin trnh mc s cp cc lnh iu c t ngay trong chng trnh ngi dng, iu cao cp lnh iu t trong thnh phn h iu hnh.chng trnh iu phi cng vic v iu phi chnh107 Bi 2. Cc k thut iu 1. K thut iu s cp : K thut kha trong ( n hiu) K thut kim tra v xc lp K thut semaphore108 a/ Phng php kha trong Nguyn tc t chc nu hai hay nhiu tin trnh cng nh ghi vo mt a ch no ca b nh trong th s k thut ch cho php mt tin trnh lm vic, cn cc tin trnh khc phi ch Mi tin trnh s dng mt byte trong vng b nh chung lm kha. Mi khi vo c on gng byte ny c gn gi tr bng 1 khi s dng xong ti nguyn gng, gn 0 vo byte nh du 109 chun b vo on gng mi tin trnh phi kim tra byte kha ca cc tin trnh khc Nu c byte no cha 1 th phi ch cho n khi byte nhn gi tr 0 mi vo on gng110 S NGUYN L Var c1, c2:Integer;BEGINc1:=0; c2 := 0;PARBEGINTT1: Repeat TT1:TT2:Repeatc1 := 1;c2 := 1;While c2 0 do ; While c1 0 do ;{on gng TT1}{on gng TT1}c1 := 0; c2 := 0;{Phn cn li ca TT1} {Phn cn li ca TT1}Until false;Until false PARENDEND.C kh nng c 2 TTcng ch i trc on gng!Xc lpKim tra111 S NGUYN L Nguyn nhn khng p ng yu cu iu : Kim tra v Xc lp 2 cng vic ring bit, Khong cch thi gian gia 2 cng vic, Gia 2 cng vic: Processor c th b chuyn sang cng vic khc. 1968: Dekker cng b gii thut iu , kt ni Kim tra v Xc lp thnh mt khi.112 Gii thut Dekker Var c1,c2,tt: Integer;BEGIN c1 := 0; c2 := 0; tt := 1; PARBEGIN TT1: Repeatc1 := 1;While c2 = 1 do if tt = 2 thenbegin c1 := 0; while tt = 2 do ; c1 := 1end; { on gng TT 1} c1 := 0; tt := 2;{ Phn cn li ca TT 1}Until false; TT2: Repeatc2 := 1;While c1 = 1 do if tt = 1 thenbegin c2 := 0; while tt = 1 do ; c2 := 1end; { on gng TT 2} c2 := 0; tt := 1;{ Phn cn li ca TT 2}Until falsePARENDEND.113 nh gi u im : khng i hi cng c c bit. => c th t chc bng ngn ng bt k v cho loi my ty . Nhc im : l qu phc tp, c bit khi s tin tnh v s on gng tng. trc khi vo on gng tin trnh phi ch i tch cc. Nguyn nhn: Khng cc b ho bin trong tin trnh, Mi TT phi t Kim tra v xc lp 114 b.Phng php kim tra v xc lp (TEST and SET) C s: dng lnh my TS c t cc my tnh th h III tr i. TS(Test and Set)Lm vic vi 2 binThc hin:- 2 cng vic, -Lin tcBin chungGBin ringL TS(L)L := G;G := 1;115 TEST AND SET S iu :Var l1, l2, g: Integer;BEGINg := 0; PARBEGIN TT1: Repeat l1 := 1;While l1 = 1 do TS(l1);{on gng TT1}g := 0;{Phn cn li ca TT1}Until false; TT2: Repeat l2 := 1;While l2 = 1 do TS(l2);{on gng TT2}g := 0;{Phn cn li ca TT2}Until false PARENDEND.gl1 l20 11 0 111111 10 101 111111116 c im: n gin, phc tp khng tng khi s tin trnh tng. Nguyn nhn: Cc b ho bin v tnh lin tc ca KT & XL, Tn ti hin tng ch i tch cc. Nguyn nhn: Mi TT phi t a mnh vo on gng. 117 TEST and SET c im: n gin, phc tp khng tng khi s tin trnh tng. Nguyn nhn: Cc b ho bin v tnh lin tc ca KT & XL, Tn ti hin tng ch i tch cc. Nguyn nhn: Mi TT phi t a mnh vo on gng. 118 TEST and Set Trong trng hp c nhiu tin trnh cng ch kh xc nh c tin trnh no s vo c on gng sm nht. ph thuc vo thi im gii phng ti nguyn gng ca tin trnh ang s dng. Gii thut ny ch thch hp khi bit chc chn thi gian ch i l rt nh 119 K THUT N BO Dijsktra xut 1972. xut: Mi ti nguyn gng c t tng ng vi mt bin nguyn c bit S (Semaphore), Ban u: S Kh nng phc v t.ng. gng, - 2 lnh my P(S) v V(S) thay i gi tri ca S, mi lnh lm 2 cng vic v lm mt cch lin tc.120 K THUT N BO Ni dung lnh P(S): * Dec(s); ** If S < 0 then a TT i xp hng. Ni dung lnh V(S):* Inc(s); ** If S s 0 then Kch hot TT ang xp hng. 121 K THUT N BO Thc hin: V nhiu l do, khng th ch to MT vi 2 lnh trn, Lnh P(S), V(S) th tc tng ng. m bo tnh lin tc: P(S)V(S)X l X lPhong to ProcessorGii phng Processor122 K THUT N BO S iu : Var s:IntegerlBEGIN s := 1; PARBEGINTT1:Repeat P(s);{on gng TT1}V(s);{Phn cn li TT1}Until false;TT2:Repeat P(s);{on gng TT2}V(s);{Phn cn li TT2}Until false PARENDEND.S=10-10-10TT1 voTT2 chTT2 voTT1 chTT1 voVar s:IntegerlBEGIN s := 1; PARBEGINTT1:Repeat P(s);{on gng TT1}V(s);{Phn cn li TT1}Until false;TT2:Repeat P(s);{on gng TT2}V(s);{Phn cn li TT2}Until false PARENDEND.S=10-10-10TT1 voTT2 chTT2 voTT1 chTT1 voVar s:IntegerlBEGIN s := 1; PARBEGINTT1:Repeat P(s);{on gng TT1}V(s);{Phn cn li TT1}Until false;TT2:Repeat P(s);{on gng TT2}V(s);{Phn cn li TT2}Until false PARENDEND.S=10-10-10TT1 voTT2 chTT2 voTT1 chTT1 vo123 Semaphore nh phn: Phn ln cc ti nguyn gng c kh nng phc v = 1 S nh phn. P(S): If s = 0 then Xp_hng Else s := 0; V(S): If dng_xp_hng = NULL then Kch_hot Else s := 1; Vn t tn cc th tc P v V. K THUT N BO 124 Semaphore c im: mi tin trnh ch phi kim tra quyn vo on gng mt ln sau hoc n c vo on gng hoc phi xp hng ch. Khi ch tin tnh khng phi lm g ht. Mt tin trnh no khc, sau khi ra khi on gng s nh thc tin trnh ch tin trnh ny vo on gng. 125 2. Cng c iu cp cao Cng c iu cp cao nm ngoi tin trnh ngi s dng Ngi s dng khng bit ti nguyn g v khi no thuc loi gng => H thng phi c trch nhim kim tra. nhn bit v iu . Dng chng trnh monitor (th k) iu 126 Monitor Cu trc c bit bao gm cc th tc, cc bin v cu trc d liu c cc thuc tnh :Cc bin v cu trc d liu bn trong monitor ch c th c thao tc bi cc th tc nh ngha bn trong monitor . (encapsulation). Ti mt thi im, ch c mt tin trnh duy nht c hot ng bn trong mt monitor (mutual exclusive). 127 Monitor Trong mt monitor, c th nh ngha cc bin iu kin v hai thao tc km theo l Wait v Signal nh sau : gi c l bin iu kin c nh ngha trong monitor: Wait(c): chuyn trng thi tin trnh gi sang blocked , v t tin trnh ny vo hng i trn bin iu kin c. Signal(c): nu c mt tin trnh ang b kha trong hng i ca c, ti kch hot tin trnh , v tin trnh gi s ri khi monitor. 128 Monitor 129 Monitor Mi thi im ch c mt tin trnh lm vic c vi Monitor. Monitor l mt ti nguyn lgic tng qut v l ti nguyn gng. Mi ln mun s dng ti nguyn mi h thng gn Monitor vo tin trnh. Nu c th s dng ti nguyn th tin trnh c a vo dng xp hng ch. Khi ti nguyn gng c gii phng, Monitor nhn iu khin v bt tn hiu gii phng tin trnh khi trng thi ch.130 Monitor Monitor khng phi l tin trnh m l mt i tng th ng. Monitor c kch hot khi c tin trnh cn s dng cng c ny. Thng thng Monitor c h thng kch hot khi phn phi ti nguyn. Cc tin trnh ng dng kch hot Monitor t chc iu khi mc u tin ca n khng cho php tin trnh trc tip lm vic vi cc th tc P(S) v V(S) 131 Bi 3. Tc nghn (Deadlock) 1. nh ngha 2. iu kin xy ra b tc 3. Phng nga b tc 4. D bo v trnh b tc 5. Nhn bit v khc phc 132 1. nh ngha Mt tp hp cc tin trnh c nh ngha trong tnh trng tc nghn khi mi tin trnh trong tp hp u ch i mt s kin m ch c mt tin trnh khc trong tp hp mi c th pht sinh c. 133 134 135 2.iu kin xy ra b tc 4 iu kin cn c th lm xut hin tc nghn: C s dng ti nguyn khng th chia s (Mutual exclusion): Mi thi im, mt ti nguyn khng th chia s c h thng cp pht ch cho mt tin trnh , khi tin trnh s dng xong ti nguyn ny, h thng mi thu hi v cp pht ti nguyn cho tin trnh khc.136 S chim gi v yu cu thm ti nguyn (Wait for): Cc tin trnh tip tc chim gi cc ti nguyn cp pht cho n trong khi ch c cp pht thm mt s ti nguyn mi. Khng thu hi ti nguyn t tin trnh ang gi chng (No preemption): Ti nguyn khng th c thu hi t tin trnh ang chim gi chng trc khi tin trnh ny s dng chng xong.137 Tn ti mt chu k trong th cp pht ti nguyn ( Circular wait): c t nht hai tin trnh ch i ln nhau : tin trnh ny ch c cp pht ti nguyn ang b tin trnh kia chim gi v ngc li. Khi c 4 iu kin ny, th tc nghn xy ra.138 Cc phng php x l tc nghn3 hng tip cn x l tc nghn : S dng mt quy tc (protocol) bo m rng h thng khng bao gi xy ra tc nghn. Cho php xy ra tc nghn v tm cch sa cha tc nghn. Hon ton b qua vic x l tc nghn, xem nh h thng khng bao gi xy ra tc nghn. 139 3. Phng nga b tc Phng nga b tc : m bo sao cho khng ng thi xy ra bn iu kin gy b tc. khng cn phi tc ng ng thi vo c bn iu kin. ty tnh hnh c th tc ng nhm iu kin ny hay nhm khc. Vic phng nga b tc l rt tn km-> ch p dng i vi cc h thng c xc xut xy ra b tc ln v tn tht do b tc gy ra cng rt ln140 Phng nga Ti nguyn khng th chia s : gn nh khng th trnh c iu kin ny v bn cht ti nguyn gn nh c nh. Tuy nhin i vi mt s ti nguyn c th dng cc c ch spooling bin i thnh ti nguyn c th chia s.141 Phng nga cu thm mt ti nguyn th n khng chim gi cc ti nguyn khc. C th p t mt trong hai c ch truy xut sau : Tin trnh phi yu cu tt c cc ti nguyn cn thit trc khi bt u x l Khi tin trnh yu cu mt ti nguyn mi v b t chi, n phi gii phng cc ti nguyn ang chim gi , sau li c cp pht tr li cng ln vi ti nguyn mi.142 Phng nga Khng thu hi ti nguyn: cho php h thng c thu hi ti nguyn t cc tin trnh b kho v cp pht tr li cho tin trnh khi n thot khi tnh trng b kha. Tuy nhin vi mt s loi ti nguyn, vic thu hi s rt kh khn v vi phm s ton vn d liu143 Phng nga t im gc: C nh trong CT, Theo tc nhn ngoi (vd: thigian) ng dng: Hiu chnh CT, Thc hin cc CT di, Vi ton b h thng: Hibernating. im gcDumpThi im ngt CTDumpim khi phcthc hin CT144 Phng nga Tn ti mt chu k: trnh to chu k trong th bng cch cp pht ti nguyn theo mt s phn cp nh sau : gi R = {R1, R2,...,Rm} l tp cc loi ti nguyn. Cc loi ti nguyn c phn cp t 1-N. V d : F(a) = 2, F(my in) = 12 Cc tin trnh khi yu cu ti nguyn phi tun th quy nh : khi tin trnh ang chim gi ti nguyn Ri th ch c th yu cu cc ti nguyn Rj nu F(Rj) > F(Ri). 145 4.D BO V TRNH Mi ln phn phi mt ti nguyn: kim tra xem vic phn phi ny c th dn n nguy c b tc cho mt s tin trnh no hay khng v l nhng tin trnh no? iu kin mi trng: Xc xut xy ra b tc nh, Tn tht (nu c b tc) ln. 146 D BO V TRNH Giithut tiu biu: Ngi ch ngn hng. Gi thit: Xt 1 loi ti nguyn, s lng tstb, n tin trnh, Maxi, Ffoii, Kti boolean, True chc chn kt thc c, False trong trng hp ngc li. 147 D BO V TRNH ts := tstb;{Thng k}For i := 1 to n do begin clai[i] := max[i] - ffoi[i]; ts := ts - ffoi[i]; kt[i] := falseend;{nh gi}Flag := true;While flag dobeginflag := false; for i := 1 to n do if not kt[i] and (clai[i] cc tiu trnh c th chia s cc bin ton cc ca tin trnh. Mt tiu trnh c th truy xut n c cc stack ca nhng tiu trnh khc trong cng tin trnh. khng c c ch bo v 158 Li ch 4 loi: S p ng (Responsiveness) : cho php mt chng trnh tip tc chy thm ch nu mt phn ca n b kha hay ang thc hin mt thao tc di -> gia tng s p ng vi ngi dng. VD: trnh duyt web p ng bng 1 lung nh c ti bng 1 lung 159 Chia s ti nguyn (Resource Sharing) : Mc nh chia s: b nh v ti nguyn ca tin trnh Cho php ng dng c nhiu hot ng trong cng khng gian a ch. Kinh t (Economic): tn t th gian to v qun l lung hn tin trnh VD: Solaris 2: to qu trnh chm hn 30 ln so vi lung chuyn ng cnh chm hn 5 ln 160 S dng kin trc a x l (Utilization of MP Architectures): Tin trnh n lung ch chy trn mt CPU Mi lung thc thi song song trn mt b x l khc nhau -> gia tng tnh ng hnh Trong kin trc n x l: CPU chuyn i qua li gia cc lung nhanh -> to o gic ca song song 161 2.User thread v kernel thread User thread: c h tr v ci t bi th vin lung mc ngi dng. Th vin h tr:To lung, lp lch, qun l lung c khi to v qun l nhanh, khng c s can thip ca h thng Li gi h thng -> gy nghn h thng Posix Pthreads, Mach C-thread, win32 thread 162 Kernel thread H tr trc tip bi h iu hnh To lung, lp lch v qun l c to v qun l chm hn user thread Windows NT, windows 2000,solaris 2, Tru64 Unix h tr kernel thread 163 3. M hnh a lung 3 m hnh: Nhiu - mt Mt - mt Nhiu - nhiu 164 M hnh nhiu- mt nh x nhiu lung cp user ti mt lung cp nhn. Qun l lung thc hin trong khng gian ngi dng Khng th chy song song trn nhiu b x l 165 M hnh mt mt nh x mt lung ngi dng ti mt lung nhn Mt lung khc chy khi mt lung khc thc hin li gi h thng gy nghn Nhiu lung chy song song trn cc b x l khc nhau Chi ph cho vic to lung nhn nh hng hot ng ca OS -> gii hn s lung nhn Windows NT, windows 2000 v OS/2 166 M hnh nhiu nhiu a hp nhiu user thread ti s lng < hoc = cc kernel thread Mt ng dng c th c cp nhiu lung nhn khi trong h thng nhiu b x l Ngi dng c th to nhiu lung, cc lung nhn tng ng c th chy song song trn b a x l Solaris 2 v Tru64 Unix 167 Pthreads Tham chiu ti chun POSIX (IEEE 1003.1c) nh ngha API cho vic to v ng b lung. c t cho hnh vi lung h iu hnh khc nhau ci t khc nhau 168 169 170 171 Lung Solaris 2 n bn Unix h tr lung ti cp nhn v cp ngi dng Pthread API Gia user v kernel thread l mt Lwp Mi tin trnh cha t nht mt lwp Th vin lung a hp user thread trn cc lwp Mi lwp c mt kernel thread Kernel thread hc thi tt c thao tc trong nhn. M hnh nhiu nhiu 172 Chng 3: Qun l Processor Chng trnh mun thc hin th trc tin phi np vo b nh. Nhng nu chng trnh khng c quyn s dng processor th vn khng thc hin c. processor c th c xt nh l ti nguyn phc v cho vic thc hin chng trnh. 173 1.Processor l gc v Processor vt l. Ch a chng trnh phn chia thi gian mi ngi s dng c cm gic nh ch c mt mnh mnh l ngi duy nht s dng ton b h thng. Tt c cc h iu hnh thc hin song song u do mt processor ca h thng processor vt l iu khin. ngi s dng nh gi hot ng processor trn c s quan st tin trnh ca mnh thc hin -> Processor ngi s dng quan stv nh gi : processor lgic.processor logic gn vi tin trnh.174 1.Processor l gc v Processor vt l. TT3TT1TT2t0 t1t2t3t4t5t6ttUSER 3 LP3USER 1 LP1USER 2 LP2175 1.Processor l gc v Processor vt l. Ch x l k tip n chng trnh: mt tin trnh c thc hin xong mi khi to v thc hin tin trnh khc -> c th ng nht processor logic vi processor vt l.km hiu qu v ti nguyn processor b lng ph nhiu. Nng cao hiu qu khai thc ca ton h thng ni chung: phn chia b nh phn phi thi gian ca processor cho nhiu tin trnh ng thi tn ti. i vi mi tin trnh, tc thc hin s b gim : thi gian truy nhp b nh tng khng c quyn s dng processor lin tc. i vi ngi s dng: thay i tm l khai thc h thng. 176 Cc vn cn phi gii quyt i vi cc h thng nhiu processor a)S lng processor logic nn to ra l bao nhiu? b) di khong thi gian gn lin tc processor vt l cho mt processor lgic l bao nhiu th hp l? c)Sau khi mt processor lgic ht quyn s dng processor vt l th cn chn tin trnh no phn phi processor vt l? Cc cch gii quyt khc nhau ba vn nu trn to ra cc chin lc iu tin trnh khc nhau. 177 2 - Cc trng thi tin trnhTTSn sngTTThc hinTTCh iKT CT Ch phn chia thi gian178 Mi thi im ch c mt tin trnh ginh c processor thc hin lnh ca mnh. Tin trnh ny nm trong trng thi thc hin. Tin trnh c phn phi y mi ti nguyn ch thiu processor-> trng thi sn sng. 179 Nu tin trnh khng th thc hin tip c v thiu mt vi iu kin no th n nm trng thi b ngt. Tin trnh khng th sn sng thc hin c v s kin m n cn cha xy ra tin trnh gi ti mt mul nhng m un ny cha c np v nh v trong b nh tin trnh ang thc hin trao i vo ra v thit b vo ra cha bo l xong php trao i ch nh. tin trnh b ngt khng chim b nh v ch trong mt s trng hp c th a tin trnh ra b nh ngoi. Mt s h thng thm ch cn chuyn bt tin trnh sn sng ra b nh ngoi v nh vy chuyn n sang trng thi b ngt. Nhn ton cc h thng : mi thi im ch c khng qu mt tin trnh nm trong trng thi thc hin, cn cc trng thi sn sng v b ngt c th c nhiu tin trnh. 180 Mi tin trnh, d ang trng thi no i na cng c lc nhn y mi ti nguyn, c th ch tr processor vt l. Nh vy n c mt processor logic. Giai on cung cp v gn ti nguyn cho tin trnh k c processor lgic gi l khi to tin trnh. Trong ch phn chia thi gian, tin trnh -c khi to li mi ln ngi s dng c php giao tip vi h thng. Tin trnh ny lp tc -c chuyn sang trng thi sn sng.181 Trong ch x l theo l, cng vic c t choc xp hng ch nhp v khi to, thm ch c khi c phn phi mi ti nguyn ch cn ch nhn processor lgic. Gi thit mi cng vic trong ch x l l ch tng ng vi mt tin trnh. n mt lc no cng vic c chn, tc l h thng tin hnh phn phi ti nguyn cho n. Mt tin trnh mi c khi to v c chuyn trng thi sn sng. Khi tin trnh thc hin xong h thng s ly li processor lgic v tin trnh khng cn tn ti na. hon tt mi x l theo ng yu cu ngi s dng cng vic c chuyn sang xp hng ch v s trn my v hay truyn thng tin lin lc ng di. Tin trnh ch phn chia thi gian ra thng khi h thng t trng thi thc hin bng cch tr li h thng processor lgic. 182 Tin trnh c th ri b trng thi thc hin v mt trong ba l do: Tin trnh hon thnh mi vic cn thit tin trnh tr processor lgic v c chuyn sang ch x l kt thc. Tin trnh t ngt chng hn sau khi a yu cu trao i vo ra v phi ch cho php trao i ny kt thc mi lm vic tip c. Tin trnh chuyn t trng thi thc hin sang b ngt v mi cho n khi xut hin s kin m n ch n, 183 Tin trnh s dng processor vt l ht thi gian ginh cho n v c chng trnh iu chuyn t trng thi thc hin sang sn sng. Vic chuyn trng thi tin trnh v thc cht l phn phi li ti nguyn h thng, trong trng hp ny ch yu l ti nguyn processor vt l. Cc ti nguyn khc nh b nh, my in, mn hnh u c th c phn phi li. C ti nguyn d phn phi li b nh tng i d processor d phn phi li. nht. C ti nguyn km linh hot -> kh phn phi li. My in rt kh phn phi li 184 Khng phi mi h iu hnh u phn phi li processor. Nu tin trnh b ngt nm trong b nh v s kin n ch xy ra th chng trnh iu khin s chuyn tin trnh t trng thi b ngt sang trng thi sn sng. Nu tin trnh b a ra b nh ngoi th n s c a li vo b nh trong v sau chuyn sang trng thi sn sng. T trng thi ny tin trnh chuyn sang trng thi thc hin khi chng trnh iu chn n. Nu tin trnh va khi phc c th t u tin phc v cao th c th c chuyn ngay t trng thi sn sng sang trng thi thc hin. 185 chng trnh iu khin m nhim. Vic phn phi v phn phi li processor vt l chn processor lgic Chn cng vic v xy dng tin trnh ng vi n do chng trnh iu phi m nhim. phn phi b nh trong b nh ngoi gn cc file lm vic vi tin trnh cung cp cc ti nguyn khc chuyn tin trnh sang trng thi sn sng. t chc x l kt thc tin trnh. 186 chng trnh iu m nhim chn tin trnh sn sng phn phi processor vt l cho tin trnh. Do tnh cht cng vic nn chng trnh iu i khi c gi l chng trnh iu phi cp thp , cn bn thn chng trnh iu phi th gi l iu phi cp cao. Khc bit c bn gia iu phi v iu l tin trnh ch cn mt ln c iu phi nhng c th cn c iu nhiu hn.187 3. iu tin trnh (scheduling). Mt trong nhng chc nng ca chng trnh iu l chn tin trnh thc hin, tc l chn tin trnh sn sng v phn phi processor vt l cho n. Mi tin trnh sn sng c gn mt th t u tin. Th t u tin c xc nh da vo nhiu yu t khc nhau thi im hnh thnh tin trnh tng thi giantin trnh c thc hin thi gian ngi s dng d bo kt thc. Th t u tin ny -> u tin iu ( phn bit vi u tin iu phi phc v cho hot ng ca chng trnh iu phi). Mi cch to th t u tin iu khc nhau s lm xut hin mt phng thc iu . 188 Mc tiu iu phi S cng bng ( Fairness) : Cc tin trnh chia s CPU mt cch cng bng, khng c tin trnh no phi ch i v hn c cp pht CPU Tnh hiu qa (Efficiency) : H thng phi tn dng c CPU 100% thi gian. Thi gian p ng hp l (Response time) : Cc tiu ho thi gian hi p cho cc tng tc ca ngi s dng Thi gian lu li trong h thng ( Turnaround Time) : Cc tiu ha thi gian hon tt cc tc v x l theo l. Thng lng ti a (Throughput ) : Cc i ha s cng vic c x l trong mt n v thi gian. 189 Tiu chun s lng nh gi cht lng iu l thi gian ch i x l. thi gian mt tin trnh trng thi sn sng ch c phn phi processor vt l. ngi s dng quan tmc thi gian tin trnh b ngt, thi gian ch chng trnh iu phi x l. Khi tin trnh b ngt -> khng c xt phn phi processor, thi gian tin trnh nm trong trng thi ngt khng c tnh vo thi gian ch i nh gi cht lng iu . ch phn chia thi gian s dng tp th ngi s dng khng quan tm n tng thi gian s dng processor m ch lu n thi gian cn thit phc v yu cu cui cng va a vo. i vi lp ngi s dng trong ch ny khng tn ti thng tin cn thit nh gi thi gian phc v, cng nh khng c cng c th hin c nhng nh gi nu c. 190 3. iu tin trnh (scheduling) (tip). 2 ch thng dng a. Ch mt dng xp hng b. Ch hai dng xp hng 191 Ch mt dng xp hng V nguyn tc cch thc iu tt nht l m bo cho mi ngi c phc v nh nhau. -> khng c mt tin trnh no phi ch i lu hn tin trnh khc. -> nh gi cht lng iu da vo thi gian ch i trung bnh. Gi thit h thng ang xt hot ng lu dng xp hng cho iu phi nhim v, cho iu , dng xp hng tin trnh b ngt l ln phn ng ca h thng khng thay i theo thi gian, -> h thng hot ng trong ch n nh. Khi i vi mi tin trnh chuyn sang trng thi sn sng o c thi gian ch i: khong thi gian k t khi tin trnh chuyn sang trng thi sn sng cho ti khi n chuyn sang trng thi thc hin. 192 i vi mi tin trnh ta c th c nhiu ln khong thi gian ny -> tnh c thi gian ch i trung bnh ca mt tin trnh c th. S quan st cng ln th thi gian ch i trung bnh -> cng chnh xc. nh gi cht lng iu = vic phn tch gii thut iu + kt qu thc nghim Gi thit: quan st v thng k thi gian chi i ca tng tin trnh ch khng phi ca mt tin trnh->thu c thi gian ch i trung bnh chung ca h thng.193 Chin lc phc v bnh ng l m bo cho mi tin trnh u c mt thi gian ch i trung bnh nh nhau. Chin lc FCFS (First come first served). theo trnh t xut hin ca tin trnh trong dng xp hng sn sng v mi tin trnh c phc v n khi kt thc hoc khi n phi chuyn sang trng thi b ngt. VD: Xp hng bn go n gin, d t chc: processor khng b phn phi li. Chi ph t chc FCFS l thp nht v khng phi thay i th t u tin iu v khng phn phi li processor bn thn th t u tin iu chnh l th t xut hin ca tin trnh trong dng xp hng sn sng.194 Nhc im: Nhc im c bn ca FCFS l cc tin trnh ngn cng phi ch nh nhng tin trnh di. Ngi s dng khng quan nim thi gian ch i trung bnh nh nhau l bnh ng trong phc v. Thi gian ch i trung bnh s tng v hn khi h thng n gn gii hn kh nng phc v ca mnh. Nu pht tn thi gian thc hin tin trnh tng th thi gian ch i trung bnh cng tng theo. khi gp tin trnh t b ngt th cc tin trnh khc s b xp hng lu, nhiu thi im tin trnh phI ch v hn. Mi chin lc khng phn phi li processor u c nhc im ny. 195 chin lc SJN (Shortest Job Next) khc phc nhc im FCFS -> xy dng cc chin lc m bo cc tiu ha thi gian ch i trung bnh chung. xc nh th t u tin iu trong qu trnh thc hin tin trnh ch khng phi l lc khi to. tin trnh c tng thoi gian thc hien t nht c u tin thc hin trc u tin tin trnh ngn nht. Thng thng tin trnh ny p dng trong ch khng phn phi li processor. So vi FCFS, SJN gim thi gian ch i trung bnh chung, c th l thi gian ch i trung bnh ca cc tin trnh ngn, nh hn thi gian ch i trung bnh ca cc tin trnh di.196 So vi FCFS trong chin lc ny thi gian ch i trung bnh ca cc tin trnh di ln hn, ngoi ra pht tn ca thi gian ch i cng tng. -> kh d bo c khi no tin trnh di c phc v. i vi nhiu ngi s dng d bo c kh nng phc v cng quan trng khng km tc phc v. SJN nhanh chng loi b cc tin trnh ngn, gim s tin trnh trong dng xp hng sn sng. C th p dng ch phn phi li processor trong SJN, ngt tin trnh di ang thc hin phc v tin trnh ngn hn mi xut hin trong dng xp hng sn sng. Nhng vic phn phi li processor ny ch cng lm cho cc tin trnh ngn c li hn. nu tin tnh mi c tng thi gian i hi phc v nh nhng li ln hn thi gian cn thit thc hintin trnh ang hot ng -> vic chuyn sang tin trnh mi l khng hp l. 197 Chin lc (Shortest Remaining Time) khc phc nhc im ny ->u tin tin trnh c thi gian cn li t nht (SRT) Chin lc ny i hi phi c tng thi gian phc v cho mi tin trnh. Thi gian cn li = hiu gia thi gian m ngi s dng d bo vi thi gian phc v. C th khng phn phi li processor nhng nu vy mi u im c bn ca SRT s mt theo. V vy chin lc ny thng thng c phn phi li processor tng t nh chin lc SJN c phn phi li processor. Chin lc ny m bo thi gian ch i trung bnh l nh nht. C SRT ln SJN u da trn c s c thng bo trc v thi gian cn thit phc v tin trnh -> khng thch hp vi ch s dng tp th phn chia thi gian. 198 Trong SJN v SRT th t u tin iu ph thuc vo thi gian thc hin chng trnh m ngi s dng khai bo. Thi gian khai bo cng t -> mc u tin nhn c cng cao. ->ngi s dng c th nng mc u tin iu bng cch khai thi gian t i. chng li hin tng ny c th kt thc bt thng tin trnh khi ht thi gian yu cu hoc p dng n gi khc cao hn i vi thi gian ph tri. lu : d p dng chin lc iu no thcng vn gp nhng tin trnh b lp v hn ln -> v vy vi mi tin trnh u phi p dng gii hn thi gian phc v. Gii hn ny ph thuc vo tng lp bi ton hoc xc nh ring cho tng tin trnh. Khi tin trnh c phc v ht thi hn ti a n s b bt buc phi kt thc bt thng. 199 gim thi gian ch i trung bnh, h thng c th xc nh s th t u tin iu cao cho tin trnh c kh nng s dng t thi gian processorvd: cc tin trnh cn trao i vo ra nhiu -> nhn c s u tin cao. thng p dng trong ch nhiu dng xp hng. 200 phng php vng trn RR (Round Robin). Mi tin tnh trong dng xp hng ln lt c phn phi mt lng t thi gian thc hin. Sau khong thi gian , nu tin trnh cha kt thc hoc khng ri vo trng thi ch i th n c chuyn v cui dng xp hng sn sng. cc tin trnh xp hng vng trn v lun lun c m bo phc v v vyh sm hay mun cng s kt thc. Khi c tin trnh mi, n s c a vo dng xp hng vng trn, t v tr s c phc v ngay lp tc. cc tin trnh ngn, di u c coi nh nhau. 201 c th u tin thch ng vi tin tnh di -> phn cc tin trnh thnh m lp, lp th i tin trnh c phc v Ki ln, mi ln vi thi gian Ti. Nu sau thi gian dnh tin trnh cha kt thc hoc khng b ngt th n c chuyn sang lp (i+1), vi thi gian phc v Ti+1 > Ti. Lng t thi gian phc v tng dn cho n khi tin trnh ri vo lp cui cng lp M, n s c phc v vi lng t Tm khng i. th t u tin iu tng dn theo thi gian xp hng ch i. Cch phc v ng mc theo lp nh vy -> cho php h thng u tin ngm cc tin trnh ngn v n s kt thc sm hn cc tin trnh di. Tuy vy u tin ngm ny khng gy tn hi qu ln cho cc tin trnh di. 202 Do phi thng xuyn phn phi li processor, nn thi gian ch i trung bnh chung trong RR c th ln hn so vi phng php FCFS. Tuy vy nu pht tn thi gian thc hin cc tin trnh ln th thi gian ch i trung bnh chung ca RR c th nh hn so vi FCFS. Chin lc iu vng trn c p dng rng ri trong ch s dng tp th phn chia thi gian. Trong RR kch thc lng t thi gian q ng vai tr ht sc quan trng. Nu q ln th vic b sung thm tin trnh mi hoc tin trnh c kch hot li t trng thi b ngt s lm dng xp hng di ra v iu ny lm tng thi gian ch i trung bnh. nu q qu nh th n s lm cho cc tin trnh phi lin tc chuyn trng thi v v vy gim h s hu ch trong hot ng ca processor. Tm li phi cho q nhn gi tr hp l. Thng thng q c chn trong khang 200 20 mili giy. 203 Tn ti mt vi kiu phc v khc nhau da trn c s chin lc RR. Trong ch s dng tp th phn chia thi gian ngi ta phi khng ch thoi gian phn ng khng qu t. Nu c n tin trnh sn sng th ly q=t/n. Nu xut hin tin trnh mi th cho vo dng xp hng khc-> x l xong mt lt dng xp hng ban u mi chuyn sang dng xp hng th hai. Nu thi gian chuyn processor t tin tnh ny sang tin trnh khc l s th trn thc t phi chn q=t/n s. Vi t cho trc ngi ta phi khng ch s tin trnh c q nm trong gii hn hp l. Nu c kh nng d bo c thi gian trao i vo ra th c th khng ngt tin trnh khi thy php vo ra kt thc trc khi ht l-ng thi gian phc v. thc y cc tin trnh di mau kt thc ngi ta tng mc u tin cho cc tin trnh tn ti lu trong dng xp hng sn sng. Mc u tin c tnh theo hiu gia thi gian hin ti vi thi im khi to tin trnh sn sng. Tr s cng ln th mc u tin cng cao. 204 Ch nhiu dng xp hng. Da vo thng tin do ngi s dng cung cp v kt qu phn tch ca h thng -> phn lp tin trnh sn sng v phc v mi lp theo mt cch. Trong ch x l l cc tin trnh c s php vo ra nhiu c xp vo lp ring v lp ny c th t u tin iu cao. c th khng cn t chc phn phi li processor, bn thn vic ngt tin trnh t ng to hiu ng phn phi li. C ba lp tin trnh phi x l ring: - Tin trnh thi gian thc - Tin trnh ca ch s dng tp th phn chia thi gian - Tin trnh x l l. 205 Tin trnh thi gian thc phi c phc v xong trc mt thi im no , thng thng do c trng thit b ngoi vi quyt nh. Tin trnh ch phn chia thi gian phi c phc v trong phm vi m ngi s dng chp nhn c, ni chung phi to cm gic nh ngi s dng c lm vic lin tc, khng h b gin on. Tin trnh x l l khng i hi nhiu v thi im v khong thi gian c phc v lin tc. Nhiu dng xp hng cho php iu tin trnh linh hot hn. Mi dng c th c chin lc ring hoc cc gi tr tham s khc nhau. mt s h thng tin trnh khng thay i lp trong sut qu trnh c phc v. C nhng h thng cho php hcuyn tin trnh t dng xp hng ny sang dng xp hng khc. 206 TTu tin caoTTu tin thpThc hinDng xp hng nn207 Mt trong s cch t chc nhiu dng xp hng hay p dng l t chc hai dng xp hng: mt cho cc tin trnh trao i vo ra nhiu, mt cho cc tin trnh tnh ton nhiu. tin trnh dng th nht c mc u tin cao hn trong thc hin, tuy vy do phi trao i vo ra nhiu chng s khng s dng ht thi gian c c. Cc tin trnh tnh ton s c thc hin da trn nn ca cc tin trnh dng xp hng th nht. Lu : tin trnh dng no th phi quay v ng dng nu cha kt thc. 208 c. m bo kt thc ng thi hn m bo kt thc ng thi hn l i hi mc cao hn m bo kt thc tin trnh. Tin trnh chng nhng phi kt thc m cn kt thc trong thi hn quy nh: Trc mt thi im no hoc sau khong thi gian nht nh, cc tin tnh thi gian thc v tin trnh ca ch phn chia thi gian i hi c rng buc cht v thi gian. C th iu phi cc tin trnh i hi cht ch v thi hn khng kh khn lm bng cch sp xp tin trnh theo th t thi im cn kt thc. Nhc im ca cch tip cn ny l c th c tin trnh c phc v nhanh hn mc cn thit v nh hng ti cc tin trnh khc cn nhiu thi gian processor. Chng hn mt tin trnh cn 5 pht trong vng 20 pht ti. Nu tin trnh ny c th t u tin cao, n s c thc hin ngay mc d cha tht cn thit v lm mi tin trnh phi ch i 5 pht lin k c cc tin trnh ngn. Gii php trong trng hp ny l phn phi processor nhiu ln cho tin trnh, b tr ri rc trong sut qu trnh m n cn. Gii thut ny thng p dng vi cc tin trnh thi gian thc v i vi loi tin trnh ny quan trng l thi im kt thc. 209 Ngt v x l ngt:nh ngha : tin trnh c th thc hin chnh xc cn c s phi hp nhp nhng gia hot ng ca processor vi hot ng ca cc thit b vo ra v ngoi v. Ngt l phng tin cc thit b khc trong h thng bo cho processor bit vic thay i trng thi ca mnh. Trn quan im lp trnh, t gc processor : ngt ngng t xut vic thc hin mt tin trnh chuyn sang thc hin tin trnh khc khi c mt s kin no xy ra. -> vai tr ca ngt trong h thngl cng c chuyn iu khin ti mt tin trnh khc m tin trnh hin ti khng bit. 210 ALUAddrDecodeS kinNgt trongPhn loi Ngt c chia thnh hai loi chnh : ngt trong v ngt ngoi. 211 Ngt trong : ngt ng vi cc s kin xut hin bi hot ng ca chnh processor. s kin gy ra ngt trong:vic chia cho khng, trn nh... trong ch qun l b nh theo chin lc phn on hoc phn trang: truy nhp ti trang hoc on cha np vo b nh. Nhiu my tnh c hai ch hot ng supervisor v ch ngi s dng. ch supervisor mi lnh u c th thc hin c. ch ngi s dng th ch mt phn ca h lnh c m bo thc hin. lnh ch thc hin c trong ch supervisor gi l lnh h thng. trong ch ngi s dng processor gp lnh h thng -> xut hin ngt trong. 212 Ngt ngai xut hin khi xy ra cc s kin nm ngoi tin trnh ang thc hin. VD: tn hiu t ng h, mt ngun, c s c k thut trm trng .... (Cc s kin gy ra bi cc thnh phn nm ngoi h thng tnh ton). - Ngt chn c v ngt khng chn c. Ngt chn c : cc ngt m b x l c th b qua khng x l. VD : nh ngt ng h (c mi xung nhp li xut hin mt ngt). Ngt khng chn c : cc ngt m b x l khng th b qua c. VD : s c k thut, hng hc -> my tnh khng hot ng tip c. 213 - Ngt cng v ngt mm. Ngt mm : nhng li gi ngt thng c t ngay trong chng trnh ngi s dng. VD : Lnh intr trong Pascal. trong C.. Ngt cng : cc ngt gy ra bi processor v cc phng tin k thut H thng nh k sau khong thi gian nht nh xem xt c tn hiu ngt hay khng. Tham s k thut ny l rng buc phi lu khi xy dng cc chng trnh h thng. 214 TT b ngtTT x l ngtS kin(Event)12345Mc x l IMc x l IICc bc x l ngt 215 Ba bc u do phn k thut m nhim. Hai bc sau do h iu hnh thc hin. X l s kin c m bo bng chng trnh x l ngt. Mi loi s kin chng trnh x l ngt ring. chng trnh x l ngt lu li cc thng tin v trng thi ca tin trnh ngt216 Phn tip theo l on chng trnh x l s kin. Mi loi s kin i hi mt cch x l ring, n gin nh xc lp mt vi bit trong thanh ghi c hoc khi trng thi phc tp nh x l sai st khi c a t. Nu s kin khng i hi phi x l gp th h thng c th a tin trnh x l vo dng xp hng sn sng. Phn cui: khi phc trng thi tin trnh b ngt m bo cho h thng tip tc hot ng bnh thng. Nu tin trnh b ngt khng th tip tc thc hin v s kin xy ra( chng hn v l do b trn nh trong tnh ton) -> sau khi thng bo nguyn nhn chng trnh ngt chuyn tin trnh b ngt sang b phn x l kt thc. 217 Mt s hnh ng trong x l ngt phi c thc hin ngay lp tc nh trng thi tin tnh, x l li... chng trnh thc hin cc x l ny phi thng trc trong trong b nh v l mt b phn trong nhn ca h iu hnh. x l t cp bch hn s do cc chng trnh khng thng trc m nhim. -> bn thn x l ngt thng c chia thnh hai mc. ngt lin quan ti iu khin v hot ng ca processor thng c chuyn ti chng trnh iu ngay lp tc kch hot tin trnh tng ng. -> trong dng xp hng sn sng lun lun c cc tin trnh h thng m bo iu phi, thu thp thng tin thng k, phc v x l ngt mc hai... Khi ch c mt processor th bn thn cc tin trnh h thng cng phi xp hng ch x l. 218 Ngt kp cc s kin gy ngt xut hin ng thi hoc c cc thit b k thut ghi nhn cng mt thi im. ngt c th xut hin ngay trong lc ang x l ngt. gii php x l ngt kp : gn cho mi loi ngt mt th t u tin. Nu xy ra ng thi nhiu ngt th ngt c u tin cao nht s c x l trc.219 t chc stack-> khng cn gn u tin iu cho ch-ng trnh x l ngt, Ngt c th c m hay b chn. Khi b chn, tn hiu ngt khng tc ng ln hot ng ca processor. Ngt b chn c th b mt hoc c xp hng x l. Nu c xp hng th sau khi c lnh m chn h thng s x l cc ngt xp hng. Nu ngt mi xut hin ngay trong lc x l ngt th n c th b chn hay c x l ngay ty quan h c th ca hai ngt : nu c x l th tin trnh x l ngt c tr th tin trnh b ngt, nu b chn ngt mi c th b mt hay c xp hng ch x l. Khi tin trnh x l ngt ri vo trng thi ch (b ngt) th n c y mi cho n khi chng trnh iu khin chuyn sang trng thi sn sng tip nhn. iu ny xy ra khi processor gp lnh m chn. 220 h thng hot ng c bnh thng mt s loi tn hiu phi ti c processor trong mi lc, mi ni, nu xut hin, chng hn tn hiu c sai st k thut trm trng hoc tn hiu nhp ng h. Vic chn hoc m cc chn ngt khc c th m bo bng phng tin k thut hoc phn mm, do ch-ng trnh x l ngt quyt nh. Khi ang x l ngt no , nu xut hin tn hiu ngt cng loi th tn hiu ngt phi b chn trnh vic ghi thng tin vo cng mt b nh dnh cho loi ngt . Sau khi x l xong ngt mc th nht, h thng phi m ngt x l tip ngt ang b chn. 221 Nu c thit b k thut h tr phn phi b nh khc nhau cho tng mc u tin th vic x l ngt kp bng phng php gn mc u tin s n gin i nhiu. X l ngt khng nht thit phi tin hnh lin tc. V d x l ngt vo ra c th chia thnh hai giai on giai on mt x l kt qu cc php kim tra mc knh v thit b. Giai on ny thc hin kh nhanh. Giai on th hai x l kt qu chnh php vo ra lu hn nhiu so vi giai on trc. Trong khong thi gian gia hai giai on h thng c th i x l ngt khc nu c. 222 Phn bit chng trnh con v ch-ng trnh x l ngtRetCallCT chnhCT conC ch CT conTT b ngtS kinIretKhi phcCT x l s kinC ch x l ngt223 Chng trnh ngt nm thng tr trong b nh chng trnh con th khi no c gi mi np vo b nh Chng trnh con c th b ngt cn chng trnh x l ngt th khng. Tham s ca chng trnh x l ngt th lu thanh ghi Trong b nh mi chng trnh x l ngt ch c mt phin bn duy nht. Chng trnh con c th c nhiu phin bn. 224 5) H thng ngt ca IBM PC v x l ngt trong MS DOS My tnh IBM PC c th phn bit c 256 tn hiu ngt khc nhau. Mi tn hiu ngt li c th chia thnh nhiu tr-ng hp ring gi l cc chc nng. Cc ngt c nh s ln lt t 0 tr i. Mt s ngt c quy nh dnh cho ngi s dng t nh ngha v dng vo mc ch ring ca mnh. V d: cc ngt phc v vit chng trnh phc v web,gi mail..., Mt s ngt khc cn d tr.225 qun l ngt ngi ta xy dng bng qun l ngt. PC dng 1024 bytes u tin ghi cc con tr ch ti chng trnh x l ngt, mi con tr chim 4 bytes. Chia lm hai phn mt phn cha du hiu ngt (VD : 0 : li chia cho khng, 1C : ngt ng h), mt phn cha s hiu ngt. Vng b nh ny -> vect ngt.226 Ngt v phc v ngt cu DOS Ngt 00h : Chia cho 0 : Ngt 01h : Thc hin tng lnh Ngt 02h : NMI (non-maskable interupt) Ngt 3h :Thc hin n im dng Ngt 04h :Trn nh. Ngt 05h : Copy mn hnh 227 Ngt 06h-07h : cha c s dng. Ngt 08h : Ngt ng h. Ngt 09h : Ngt bn phm Ngt 0Ah-0Ch : thay i ty theo tng my. Ngt 0Dh : a cng Ngt 0Eh : a mm Ngt 0Fh : My in228 Ngt 10h : Ngt mn hnh Ngt 11h : Xc nh cu hnh Ngt 12h : Xc nh kch thc b nh Ngt 13h : a mm Ngt 14h Giao din ni tip Ngt 15h Ngt Cassette c (ch dng vi h my AT) 229 - Ngt 16h Bn phm - Ngt 17h My in - Ngt 18h gi BASIC trong ROM - Ngt 19h Khi ng my - Ngt 1Ah Ngy gi - Ngt 1Bh Bn phm : X l phm Ctr +Break - Ngt 1Ch Ngt chu k (18,2 ln 1 giy) 230 - Ngt 1Dh c s dng nh mt con tr a ch bng mn hnh - Ngt 1Eh a ch bng a - Ngt 1Fh a ch bng k t - Ngt 20h Kt thc chng trnh : - Ngt 21h gi Hm ca DOS - Ngt 22h tr ti mt th tc kt thc ch-ng trnh 231 {$M 600,0,0} Program Vdngat ; Uses DOS, crt ; Var demnhip : longint absolute 0 :$46C ; Ngat1c :procedure ; Procedure ngatmoi ; interupt ; Var x,y :integer ; Gio,phut,giay,tg :longint ; Begin Inline($9c) ; {cat cac tham so vao ngan xep} Ngat1c ;{goi lai ngat 1c cu de tang bo dem} x :=wherex ;y :=wherey ; gio:=demnhip div 65543; tg:=demnhip mod 65543; . 232 phut:=tg div 1092; tg:=tg mod 1092; giay:=tg div 18; gotoxy(1,1);write(gio:2,-,phut:2,-,giay:2); gotoxy(x,y); end; Begin Getintvec($1c,@ngat1c); Setintvec($1c,@ngatmoi); Keep (0); End 233 Chng 4: Qun l b nh Bi 1. Mt s khi nim lin quan n b nh Bi 2. Cc khi nim lin quan n qun l b nh 234 Bi 1. Mt s khi nim lin quan n b nh B nh chia thnh 3 loi - B nh chnh (main memory): lu tr cc lnh chng trnh v d liu ang c s dng. +t +dung lng thp + hiu nng cao - B nh th cp/b nh ngoi (Secondary storage): Lu tr cc chng trnh v d liu cha cn s dng. + R + dung lng cao + chm - B nh tc cao (cache) Tc truy cp cao, thng nm ngay trong b x l. Lu tr bn sao ca cc d liu thng c s dng truy cp nhanh hn. 235 236 2 - Cc bc x l chng trnhng dng Phn ln cc chng trnh c vit di dng ngn ng thut ton. Chng trnh ban u ny phi c dch sang ngn ng thc hin ca h thng. Phn h thng lp trnh m bo chuyn i sang biu din t ngn ng thut ton sang ngn ng my. 237 CT Tn users Tn trongM un chHm tnHm a ch.OBJL thuyt chng trnh dchPh.tch c php + ph. tch ng ngha + Sinh m + Ti u ho

238 M un chM un thc hinCT thc hinThc hin KQBin tp(Link)Np v nh v(Fetch)Qun l b nhQLTin trnhQLProcessor.COM.EXE239 3 - Cc loi cu trc chng trnh: a) Cu trc tuyn tnh sau khi bin tp, cc m ul c tp hp thnh mt chng trnh hon thin, cha y thng tin c th thc hin (tr d liu vo). Mi bin tr ngoi u -c thay bng gi tr c th. thc hin ch cn nh v chng trnh mt ln vo b nh. VD: Cc tp *.com trong h iu hnh MS DOSm0m1m2. . . . . . mnl

240 Cu trc tuyn tnh u im: n gin, d t chc bin tp v nh v. Thi gian thc hin l nhanh nht v mi cng vic chun b u c thc hin trc, h thng khng cn phi bin tp thm, khng phi tm v np thm g tr d liu vo. Thi gian thc hin chng trnh thng c dng lm chun nh gi, so snh cc phng php t chc khc nhau. Tnh linh ng cao: d dng sao chp chng trnh mang sang cc my khc cng loi v cng h thng m vn duy tr kh nng thc hin. Nhc im :lng ph b nh, mc lng ph t l vi kch thc chng trnh.241 m0m0m0m0m0m2m2m2m1Cu trc ng242 Mi m ul c bin tp ring bit. Khi c thc hin, h thng nh v m ul gc. Cn ti m ul no phi s dng cc lnh macro h thng (Load, Attach, Delete) . . . np xin b nh v np tip m ul tng ng. Khi s dng xong c th gi cc lnh macro khc gii phng b nh. Trong cu trc ny trch nhim np v xa m ul do ngi s dng m nhim. Cc lnh np v xa phi c nu ngay trong chng trnh ngun. iu ny i hi ngi s dng phi nm vng chng trnh ca mnh v cc cng c iu khin b nh ca h iu hnh. 243 Nu qun l b nh tt th cu trc ny rt tit kim. Sai lm trong iu khin s gy lng ph b nh v tng thi gian thc hin. Thi gian thc hin ln: song song thc hin vi tm kim, np v nh v. Do phi n nh trnh t nh v m ul ngay bc vit chng trnh ngun, chng trnh s b ph thuc vo tng phin bn c th ca h iu hnh. Km lu ng kh np, cp nht, xo. N thch hp cho cc chng trnh h thng. 244 Cu trc overlay gii bi ton ngi ta chia chng trnh thnh cc chng trnh con nh vy th c th m t cu trc chng trnh di dng cy. mt thi im chng trnh hot ng theo mt nhnh cy no v do vy thi im ny ch cn np cc m un trn mt nhnh l . Gi s s nt trn cy l n , s nt trn mt nhnh di nht l m (m khng xut hin li gi ng mc. x l cc li gi ng mc chng trnh bin tp phi to ra mt bng thng tin iu khin na, nh supervisor overlay bit c cc m un gi v c gi. 249 C hai cu trc va xt trn u c c trng l nh v ng. Chnh cch nh v ng cho php ta s dng -c nhiu b nh hn phn b nh m h thng dnh cho ch-ng trnh. Mc d nh v c tin hnh trong qu trnh thc hin ch-ng trnh, nhng nhn chung cu trc chng trnh vn mang tnh cht tnh, n khng thay i trong tt c cc ln thc hin chng trnh. So vi cu trc ng cu trc overlay c u im l i hi ngi s dng cung cp nhng thng tin n gin v khng gn c nh cu trc vo chng trnh ngun. Nu ngi s dng xy dng c s overlay tt v cc m ul c di hp l th cu trc overlay mang li hiu qu khng thua km cu trc ng. cc chng trnh ng dng h thng phn ln u c cu trc overlay.250 Nhc im: + Vn yu cu ngi s dng cung cp thm thng tin ph. + Hiu qu tit kim b nh vn ph thuc cch b tr, t chc cc m ul ca chng trnh. Ch cn c vi m ul kch thoc ln cc mc overlay khc nhau l hiu qu s dng b nh gim st hn. + Do cu trc chng trnh l tnh -> cung cp thm b nh t do, hiu qu s dng chng trnh ca h thng cng khng i. 251 Cu trc phn onm0m1m2m3m0m1RAM252 Chng trnh ca ngi s dng oc bin tp ring tng m ul c lp. Kt qu tp hp chng tnh l mt bng iu khin cho bit ch-ng trnh c th s dng nhng m ul no, di mi m un l bao nhiu. Bng iu khin ny c gi l bng qun l on v k hiu l SCB (segment control block). SCB cn cha mt s thng tin tr gip nh v chng trnh, mi giai on thc hin h thng s da vo SCB np cc m ul cng thit vo trong b nh. Khc vi cc cu trc xt, trong cu trc ny chng no cn ch th h thng cn np tip cc m ul mi. Gp trng hp thiu b nh-> a bt ra ngoi mt s m ul c kh nng khng s dng li na. khng i hi ngi s dng phi khai bo thm bt k mt thng tin ph no, mi cng vic u do h thng m nhim khi dung lng b nh t do tng -> tc thc hin chng trnh cng tng theo. 253 Nhc im: hiu qu s dng b nh ph thuc nhiu vo cch phn chia chng tnh thnh cc m ul c lp. Cng nh cu trc overlay, ch cn tn ti vi m ul di ln l hiu qu s dng b nh s gim mt cch ng k. Cu trc ny ch p dng ch khi b nh c qun l theo kiu phn on. 254 Cu trc phn trangp0p1p2p3p4p5p6RAMp0p2255 Chng trnh c tp hp nh trong trng hp c cu trc tuyn tnh nhng sau c chnh chng trnh bin tp chia thnh tng phn c di bng nhau gi l trang. Sn phm bin tp l mt bng qun l trang, mi phn t ca bng ng vi mt trang ca chng trnh ngi s dng. Khi thc hin, supervisor qun l trang s theo di, m bo a trang cn thit vo b nh trong. Cu trc phn trang ni chung ch pht huy c hiu qu khi b nh c qun l theo cc chin lc kiu phn trang. Trong thc t, chin lc phn trang thng c p dng vi tng mul chng trnh v vi phng php qun l d liukiu phn trang. 256 Bi 2. Cc chin lc qun l b nh 1)Chin lc phn chng c nh 2)Chin lc phn chng ng 3)Chin lc phn on b nh 4)Chin lc phn trang b nh 5)Chin lc phn trang kt hp phn on 257 1)Chin lc phn chng c nh b nh c chia thnh n phn , mi phn s dng nh mt b nh c lp, gi l mt chng. b nh c phn ra bao nhiu chng - >c th np vo by nhiu chng trnh v t chc thc hin ng thi cc chng trnh s chng trnh ng thi c iu khin thc hin -> h s song song ca h thng. n chng -> h thng c h s song song khng vt qu n. V c thc hin nh mt b nh c lp nn mi chng trnh c mt danh sch qun l b nh t do cha s dng ring. Mt chng trnh c np vo chng no s tn ti cho n khi kt thc. 258 - u nhc im: Chin lc ny c u im l n gin, t chc bo v, gim thi gian tm kim. Chnh v vy n c p dng ph bin trong vic qun l cc a t dung lng ln, trong phn phi b nh cc my SERVER phc v mng. Nhc im ca chin lc ny l b nh b phn on do c th c hai kh nng xy ra: tng b nh t do cn ln nhng khng th s dng np tip chng trnh khc. Kh nng th hai l ton b nh ang rnh nhng v chng tnh c kch thc ln hn kch thc chng ln nht. Chng trnh s khng bao gi thc hin c khi chng b nh khng b phn li. Mi chng c gn vi mt s lp phc v. Chng trnh trc khi np vo h thng cng c phn lp theo khai ba ca ngi s dng. Mi chng ch phc v cc chng trnh thuc lp mnh qun l. Nh vy ta c th trnh c vic np chng trnh nh vo vng b nh ln, trnh lng ph b nh. sa i cu trc chng, ng nhin ch cn np li h iu hnh, nh-ng nh vy, trnh mt ht thng tin, ta phi ch mi chng trnh kt thc. Cng c sa i cu trc chng trnh cho php kt hp vi chng k nhau thnh mt chng kch thc ln hn. Thng tin cc vng khc vn c bo ton. 259 - Phng php qun l b nh: chin lc ny b nh ch c mt danh sch qun l b nh t do thng nht. Khi cn thc hin chng trnh h thng s phn phi vng b nh thch hp, lp phiu qun l ring, to thnh mt vng b nh c lp. Nh vy nu cc chng trnh b th ngi ta c th np vo b nh v ng thi thc hin nhiu chng trnh. Ngc li khi chng trnh c kch thc ln th ch n thun gim h s song song ca h thng. 260 u nhc im u: khng phi sao chp cc m ul chng trnh iu hin thnh nhiu phin bn v ghi vo nhiu ni nhc im: gy ra hin tng phn on b nh: sau mt khong thi gian hot ng lin tc cc chng trnh phn b ri rc khp ni v b nh t do c xu hng chia thnh nhiu mch nh. Do h thng vn qun l y nhng khng s dng c cc vng b nh cn trng. khc phc phi trang b cng c b tr li b nh -> SWAPPING261 Swapping .b tr li l: - Tm thi im thch hpln lt dng cc ch-ng trnh ang thc hin -a mt s hoc tt c cc chng trnh b nh trong cng vi trng thi ca n ra b nh ngoi, tr b nh phn phi v cho m ul qun l ca h thng. - Ti nh v chng trnh t b nh ngoi vo b nh trong, khi phc trng thi ra tip tc thc hin. 262 246246B nh t do263 y l mt cng vic ht sc phc tp v tn thi gian. Thi im thch hp dng chng trnh l thi im cc gi tr c tnh xong v lu vo b nh hay thanh ghi. Ch c lc ta mi lu v khi phc trng thi cng vic c. Do vic a chng trnh ra v nh v li cng vi vic khi phc trng thi l phc tp nn ngi ta c th khng cn a ht mi ch-ng trnh ra. Mi khi mt chng trnh c a ra ngoi b nh phn phi cho n c gii phng v c kh nng mc phn on ton b nh gim. Qu trnh a ra sau b tr li c th dng th tm c vng b nh t do thch hp hoc gim h s phn on xung mc an ton. Vic ti nh v hoc l v cng phc tp, phc tp hn c chng trnh bin tp, lin kt v chng trnh ng dng c th hot ng theo nguyn l macro processor: to ra cc cu lnh v thc hin trong qu trnh lm vic. h thng d dng phn bit u l d kin ng, ph thuc vo v tr nh v cc loi my v h thng khc nhau c nhng c ch khc nhau gip chng trnh b tr li khng lm ln gia cc a ch v hng. 264 Chin lc phn on b nh( Segmentation) Nhc im ca cc chin lc trn l khng thc hin c cc chng trnh c kch thc ln hn kch thc b nh vt l. Ngoi ra h s tch cc ca cc byte trong b nh cng khng u. Nhng byte c gi l tch tc nu ni dung ca n c s dng thc hin cc cu lnh trong thi im quan st. Nu khong thi gian quan st khng qu b ( vi phn trm giy cho cc my tnh hin i) mt chin lc s dng b nh tt l chin lc cho tp cc byte tch cc ln. Ngi s dng hon ton khng quan tm chng trnh ca h c b tr nh th no trong b nh: lin tc hay khng lin tc. V vy c th bin tp ring tng m ul v xy dng bng thng tin cho bit chng trnh s dng m ul no, di cc m ul l bao nhiu. Bng thng tin ny c gi l SCB (Segment Control Block bng qun l phn tin on).265 m0m1m2m3SCB(Segment Control Block)SCB = {Phn t}D A lDu hiu np m un:0 - Cha np,1 - np.a ch np m un di m un- Cp pht b nh,- Bo v,266 Khi thc hin SCB c np vo trong b nh. a ch u ca n oc a vo thanh ghi qun l on Rs. a ch truy nhp d liu c biu din di dng cp (s,d), trong s l s hiu segment (m ul) cn truy nhp v d- a ch t-ng i tnh t u segment. truy nhp ti mt d liu cn phi hai ln hng ti b nh. Ln th nht h thng ly ni dung ca thanh ghi qun l on Rs cng vi s v t tm c phn t th s trong Control Block. Nu du hiu D ca phn t l 0 th h thng s lm cc th tc np m ul vo b nh, xin cp pht b nh ( theo kch thc ghi trng L), tm m ul tng ng b nh ngoi, c v nh v vo vng b nh c cp pht v sau sa li ni dung trng a ch A n ch ti m ul th s. D nhin nu khng tm c th h thng s bo li v ngng thc hin. Du hiu D bng 1 chng t m ul c nhp vo b nh. Nh vy sm hay mun du hiu D cng s c xc lp bng 1, h thng s ly ni dung trng a ch A cng vi D, truy nhp ti b nh ln th hai theo a ch tnh oc c hay ghi d liu. 267 1. . .. . .300314315300Rs =15 4532sd+12352123521000+168841000M un 15RAMRAM268 u nhc im, u im : khng i hi cng c t chc c bit -> c th p dng trn my bt k. nhc im : hiu qu s dng b nh ph thuc vo cu trc chng trnh do ngi s dng vit. 269 - Phn on ngoi v b tr li (swapping). sau mt thi gian lm vic b nh b phn on ngoi ->cn cng c b tr li. Vic b tr li n gin v c s h tr ca SCB. Phn t tng ng s b nh du 0 trng D v b nh xc nh theo hai trng cn li tr v danh sch qun l b nh t do. xut hin nhu cu b tr li -> chn m ul a ra. - a ra m ul tn ti nht trong b nh. - a ra m ul c ln s dng cui cng cch y lu nht. - a ra m ul c tn sut s dng thp nht. 270 Chin lc phn trangPhng php qun l b nh: b nh c chia lm nhng phn bng nhau gi l trang. cc trang c nh s th t t 0,1,2 tr i to thnh a ch trang. Trang c dng lm n v phn phi b nh. truy nhp ti d liu a ch truy nhp c biu din di dng (p,d) trong p- s hiu trang cn truy nhp, d- a ch tng i tnh t u trang. Thng thng kch thc trang l kch thc l ly tha ca 2.271 Page0Kch thc trang:256B512B1 KB2 KB4 KB1234567a ch trang272 S trang b nh vt l ph thuc vo kch thc trang, kch thc b nh vt l. S trang ca b nh logic th ty v khng cn a ht mt lc cc trang vo trong b nh, nhng trang cha a vo c th lu tr b nh ngoi, trn a t hoc cc b nh c tc cao hn (a t vi u c c nh ) Cc trang b nh logic khi lu tr b nh ngoi chim mt vng b nh lin tc. Nhng khi c nh x vo b nh vt l, khng nht thit phi t lin tc nhau. Ln lt cc trang ca mt chng trnh c np vo b nh v c nh x vo tp khng sp xp cc trang vt l. nh x mang tnh cht b phn v khng phi mi trang u nht thit c np vo b nh vt l ngay c khi kch thc cho php273 T chc thc hin: Gi thit b nh logic c t chc trn a t, khi np chng trnh vo b nh h thng xy dng mt bng qun l trang bng PCB (page control block). Bng qun l trang dng xc lp quan h gia trang vt l v trang logic. Bng qun l trang bao gm nhiu phn t, mi phn t tng ng vi mt trang logic v c hai trng. 274 PCB = {Phn t}DPAPDu hiu np trang:0 - Cha np,1 - np.a ch np trang275 a ch ca bng PCB c np vo thanh ghi qun l trang Rp. truy nhp ti d liu h thng cn hng ti b nh hai ln: ln th nht: h thng ly ni dung Rp cng vi p trong a ch (p,d) truy nhp ti phn t th p tng ng vi trang p cn truy nhp. Nu du hiu D=0 th c ngha trang cn tm cha c, h thng s to ngt np trang cn thit vo b nh. Cng vic ny do chng trnh iu khin ca h thng m nhim. Nh vy sau khi truy nhp ti phn t th p trong PCB, sm hay mun du hiu D ca n cng c xc lp bng 1 v trng Ap s cha a ch trang trong b nh vt l. Tip theo, h thng ly a ch trang Ap ghp vi d to ra a ch vt l ca d liu a vo truy nhp ti ni dung a ch ly ra cu lnh hoc d liu cn tm. 276 1. . .. . .400480481400Rp =81 532pd+123123000123532Trang 81RAMRAMS truy nhp ti d liu 277 Chin lc phn trang cn c u im l khng xy ra hin tng phn on ngoi b nh. Nu cn b nh t do th kch thc phi phn trang -> bao gi cng ch a trang mi vo tnh trng thiu b nh ch thc s xy ra khi tt c cc trang ca b nh vt l thc s c s dng ht. 278 Qua cch t chc thc hin chng trnh xt trn, ngoi bng qun l trang PCB cn cn b nh cha cc trang d liu v chng trnh. S trang dnh cho mt chng trnh cng nhiu th tc thc hin chng trnh cng cao nhng h s song song cng gim. Khi gim s trang dnh cho mt chng trnh th h s sng song tng nhng tc thc hin ch-ng trnh gim v thng xuyn b ri vo tnh trng thiu trang cn thit thc hin. Hiu qu chung ca phng php ph thuc vo cch np trang v cch thay th trang tch cc. 279 Chin lc np trang. Bin php n gin nht l np tt c mi trang ca mt chng tnh vo b nh ngay t u, nh vy khng th xy ra tnh trng thiu trang tch cc khi thc hin. Chin lc phn phi gin n vi cu trc phn trang. Trong chin lc ny b nh ngoi khng c s dng m rng b nh trong. u im ca chin lc l vic np v nh v chng trnh vo b nh trong ht sc n gin khng pht huy c cc u im c th ca cu trc phn trang. 280 phng php np trc cho php gim kh nng thiu trang tch cc m khng cn dng ti khng gian nh vt l qu ln Phng php cho php ngi s dng to chng trnh b nh logic vi kch thc ty , ng thi h thng c th duy tr h s song song cn thit cho hot dng c hiu qu ca ton h thng. im mu cht ca np trc l d bo trang tch cc sp cn ti trong qu trnh. Nu xc nh c ng, c th np trc cc trang ny vo b nh v gim trng hp thiu trang khi thc hin chng trnh. vic d bo trang no sp c s dng l cc k kh khn. Trong ch np trc chi ph np trc cc trang khng dng n c th vt xa chi ph dnh cho vic np cc trang thc s c s dng. 281 Thng thng phng php np theo yu cu hay c dng : trang ch c np khi xut hin yu cu truy nhp ti d liu trong trang. mi ln np trang u thc s l cn thit. Khi c cch phn b trang hp l, cch t chc tm kim tt cc trang b nh ngoi c ch phn trang s m bo hiu qu khai thc trong ch c h s song song cao.282 Chin lc i trang Nu vn cn b nh t do th khng cn thit phi thay trang. Khi thiu b nh, ta phi a mt trang no ra b nh ngoi, a trang khc cn thit cho vic tip tc thc hin chng trnh vo b nh. Tn ti nhiu phng php chn trang a ra, gii phng ch cho trang mi. cc tiu ha s php x l thc hin, h thng phi kho st thuc tnh ca trang cn gii phng. T tng ch o l phi thay th trang m ln s dng tip theo cng xa cng tt. Trng hp l tng l trang khng cn cn thit cho vic thc hin chng trnh.283 Hai phng php n gin t chc l thay vng trn hoc thay ngu nhin cc trang ang dng. trong trng hp ny kh nng thay trang cn dng l kh ln. chn trang thay th theo quy tc np trc th b thay th trc ( quy tc FIFO). trang c mt lu nht trong b nh ( ca chng trnh ny) s b thay th. Nu chng trnh xy dng theo quy tc tuyn tnh th qu tht y l mt quy tc tt. Vi cc chng trnh xy dng theo kiu lp trnh cu trc quy tc c th dn n vic a ra trang quan trng. Tuy vyphng php ny vn hp dn ngi thit k v tnh n gin. Chng trnh phn phi b nh ch vic theo di qu trnh np trang, xc nh trnh t u tin a ra. S lng trang vt l c nh -> khng c kh khn trong t chc thc hin. 284 Mt phng php ci tin l a ra trang c ln s dng cui cng cch y lu nht (Phng php LRU- Last Recently Used). Phng php ny da trn gi thit chng trnh c tnh cc b ha trong s dng, khng c cc lnh chuyn iu khin i xa cu lnh ang thc hin Tuy phng php ny khng m bo ti u ha trong mi trng hp nhng trn thc t n cng hiu qu v vy c ng dng kh rng ri. Nhc im chnh ca LRU l chi ph thc hin cao. xc nh trang a ra cn nh k r sot kim tra, thng k xem nhng trang vo c s dng. 285 Thng thng phi xy dng cc khi qun l cho tng trang v c bit ring nh du truy nhp. Bit ny c xc nh bng 1 khi c truy nhp ti trang. Chng trnh thng k s nh du thi im truy nhp v xa bit nh du. Nu trong qu trnh kim tra bit nh du c gi tr bng khng th c ngha l t ln kim tra trc n thi im ny cha c li gi no ti trang ang xt. Vic xc lp gi tr 1 cho bit kim tra tc thc hin bng cc phng tin k thut. 286 Song song vi vic xc nh thi im gi ca trang, thng k s ln truy nhp t c th tnh tn sut truy nhp. Da trn thng k ny -> t chc mt chin lc thay th khc- chin lc LFU (Last frequently Used) thay th trang c tn sut s dng ln nht. Cc chin lc thay trang ni trn c th p dng chung cho ton b h thng hoc p dng cc b cho tng ch-ng trnh ang thc hin. Khi p dng thay th ch thay th cc b h thng phi lu tr kch thc b nh dng cho ton chng trnh v cn lu trnh hin tng phn phi b nh khng u gia cc chng trnh xut hin khi khi to cc nhim v trong ch a chng trnh. 287 Chin lc np trang theo yu cu gii phng ngi s dng khi vic cung cp cc thng tin ph hoc t mnh iu khin qu tnh thay i trang. chi ph t chc c ch phn trang ln v phi u t k thut m bo qu trnh bin i a ch khi nh v trang. Trong mt s trng hp, bn cnh phng tin k thut vn phi tn thm thi gian xl bng con ng chng trnh. H thng cng phi tn nhiu ti nguyn nh du qu trnh truy nhp trang v trao i vn b nh ngoi khi thay trang truy nhp. Tng thi gian thc hin chng trnh tng khi thng xuyn phi np li trang. 288 C ch phn trang m bo c h s song song cao, n cha gii quyt ht mi vn ny sinh m bo hiu qu khai thc ti a. Kch thc chng tnh v d liee ni chung khng hn ch, nhng khi b nh logic dnh cho chng trnh v d liu qu ln th bng qun l trang PCB cng ln theo v h thng phi tn nhiu b nh vt l lu tr PCB phc v thc hin. Trn thc t, cng nh bn thn chng trnh, ch mt phn bng PCB l c tc dng tch cc v trc tip trong iu thc hin cng vic v vy c th nng cao hiu qu c ch phn trang qua vic ci tin cch x l PCB. 289 chn kch thc trang thch hp. Hiu qu ca c ch phn trang ph thuc nhiu vo kch thc trang. Nu kch thc trang qu b bng PCB s ln v kh nng phi thng xuyn np li trang cng ln khi h thng hot ng gn kh nng ti hn. Nu kch thc trang ln th nh hng ca hin tng phn on trong- trang khng c s dng ht s tc ng ng k n hiu qu s dng b nh. kch thc trang phi c chn mt cch hp l v thng dao ng trong phm vi28n 210 bytes. Cc h thng ca IBM thng chn kch thc trang bng 512 byte theo truyn thng. Cc my IBM PC hin nay c b nh trong kh ln -> kch thc trang 4 kb trn thc t khng phi l qu ln. 290 Chin lc kt hp phn trang - on Phng php qun l b nh: Chin lc phn trang m bo hiu qu s dng b nh cao, khng ph thuc cu trc chng trnh ngi s dng. khc phc cc nhc im ca chin lc phn trang s dng chin lc kt hp phn trang- on. Trong chin lc ny chng trnh cng c bin tp theo ch phn on v to ra bng qun l on SCB, nhng sau mi on (segment) li c bin tp theo trang v to ra PCB ring ca tng on. 291 Du hiu np PCB:0 - Cha np,1 - np.SCB = {Phn t}D A la ch np PCB di PCB- Cp pht b nh,- Bo v,292 Trng a ch A ca phn t th I trong SCB by gi l ni cha bng PCBi nu n oc np vo b nh, trng L chia di ca PCBi. Khi thc hin chng trnh SCB tng ng s c np vo b nh v a ch u ca n cng -c a vo thanh ghi qun l on Rs. a ch truy nhp ti d liu c biu din di dng nhm ba (s,p,d), trong s l segment cn truy nhp, p l s hiu trang trong segment v d l a ch tng i tnh t u trang. 293 truy nhp ti d liu h thng cn ba ln h-ng ti b nh: 1)Ly ni dung Rs cng vi s v truy nhp ti phn t th s ca SCB. 2) Nu D bng 0 th lm th tc np PCB th I vo b nh v cp nhp ni dung cc trng D.A. Khi D bng 1 h thng cng ni dung trng A vi p truy nhp ti phn t th p trong PCB. 3) Ch i n khi du hiu p ca phn t tm c bng 1 th ghp ni dung ca trng a ch Ap tng ng vi d, hng ti b nh ln th ba ly hoc ghi d liu. 294 Trong chin lc ny b nh thng c chia lm ba phn, tng ng cha SCB, PCB v cc trang. Bn thn b nh dnh cho SCB v PCB cng thng c qun l theo ch phn trang. Chin lc ny c nhiu u im nn n thng c p dng trong cc h thng my tnh v h thng hin i. Cc my IBM PC t AT 386 tr ln u c ch qun l theo chin lc ny. Khi thiu b nh h thng c th phi b tr li cc trang d liu hoc trang b nh phc v PCB. m bo truy nhp hp thc trong ch dng chung m ul chng trnh con, mi khi cn nhp vng nh cha PCB h thng s phong ta khng cho truy nhp ti SCB. 295 6)T chc v qun l b nh trong IBM PC - My PC XT : ch thc hin c mt ch qun l gi l ch thc (real mode). Khng gianb nh vt l v khng gian b nh lgic l trng nhau. - PC AT 286 thc hin c c hai ch qun l b nh l ch thc (real mode) v ch bo v (protect mode). Cch qun l ch protect mode l theo kiu phn on. - PC AT 386 c hai ch qun l b nh l ch thc (real mode) v ch bo v (protect mode). ch bo v, cch qun l c thc hin theo hai kiu phn on v phn trang 296 My XT c dung lng b nh: 64K, 128K, 256K, 512K, 640K My AT 286 : 640 K +384 K. Vng 384K c gi l Himem. My AT 386 : 640 K + 384 K + vng >1 M Vng 640 K c gi l vng b nh c s (Base) 384 K gi l Himem hay Expand memory. Vi cc my 386 th ngi ta gi l Upper Memory. Vng b nh ln hn 1 M ngi ta gi l Extent Memory297 Cc mc c quyn (Privilege Level PL) ca cc my 80386: c 4 mc t0 n 3. Mc 0 Ht nhn: Gm cc chng trnh c s qun l ti nguyn ca my v b nh. ht nhn phi gn v c kh nng vn hnh tt. Mc 1 Qun l thit b: Cha tt c cc phn mm lin quan n HH nh qun l cc cng vo/ra, np cc cc thut ton trao i. Mc 2 Qun l file: Bao ggm cc chc nng qun l file, qun l th vin. Mc 3 Ginh cho chng trnh ng dng. 298 Nguyn tc truy nhp: chng trnh ca mt mc u tin ch c php gi v s dng d liu ca chng trnh bng hoc km mc u tin hn. Vd: chng trnh mc 1 ch c gi v s dng d liu ch-ng trnh mc 1,2, v 3. 3012NhnQLFilesThit bvPhc vH thngCTng dngMc u tin299 Ch Protect Mode: B nh c chia thnh cc khi Mi khi c qun l bi mt MCB (Memory Control Block) Mi khi MCB gm 16 byte : Byte u cha k t M hoc Z.Nu l MCB ca khi cui th l k t Z, cc khi cn li th l k t M. 2 bytes tip cha a ch an m np vo khi ny. 2 bytes tip cha di an m . 11 bytes cn li cha dng n. 300 V QUN L FILES V THIT B NGOI VI Qun l thit b ngoi vi: Cn m bo h thng thch nghi vi: S lng nhiu, Cht lng a dng, Thun tin cho ngi dng. Qun l files: Cho php ngi dng: To files cc loi b nh ngoi, Tm kim, truy nhp files, m bo c lp gia CT v thit b 301 1 Nguyn tc phn cp trong qun l thit b ngoi vi My tnh th h I v II: Processor lm vic trc tip vi thit b ngoi vi, Hn ch: Tc - S lng - Chng loi, T th h III tr ln: Processor TB iu khin TB ngoi vi (Control Devices) (Controllers) 302 ProcesorController 1 Controller 2Controller nTB Vo/RaTB Vo/RaTB Vo/Ra...Knh(Channel)- TB iu khin v TB vo/ra: MT chuyn dng H lnh + Ngn ng ring- Hot ng c lp vi nhau v vi Processor.303 ProcesorController 1 Controller 2Controller nTB Vo/RaTB Vo/RaTB Vo/Ra...Knh(Channel)CT knh(Channel Prog)Thc hin CT KnhThc hin cng vic ca mnhX l ngt vo/raNgt vo/ra (I/O Interrupt)M tr v (Return Code)TRAO I VO/RA304 Nguyn tc phn cp trong qun l thit b ngoi vi Php trao i vo ra: thc hin theo nguyn l Macroprocessor, Vi my vi tnh: Thit b iu khin vo ra I/O Card, My Card on Board, Khi nim knh b (Multiplex), Card Multimedia. 305 Knh Multiplex CONTROLLER 1CTRL 11I/O DCTRL 11I/O DI/O DKnh MultiplexKnh con306 2 - K THUT PHNG M Khi nim phng m (Buffer) ca OS. DISKBUFFERSYSTEMaread(f,a);AMBUFFERAMWrite(f2,a);SYSTEMRAMCache307 K THUT PHNG M C ch phc v phng m, Vn ng file output, FLUSH(F), Vai tr phng m: Song song gia trao i vo ra v x l, m bo c lp: Thng tin v phng tin mang, Bn ghi l gc v vt l, Lu tr v x l, Gim s ln truy nhp vt l:Gi thit mi ln truy nhp vt l: 0.01, truy nhp kiu BYTE. 308 K THUT PHNG M Khng c Buffer Buffer 512B 1B0.010.01 512B~50.01 5KB~500.1 50KB~81 309 Cc loi phng m Phng m chung hoc gn vi file, Cc H QTCSDL c h thng phng m ring nng linh hot v tc x l, Cc loi b nh Cache v phng m. Ba kiu t chc chnh: Phng m trung chuyn Phng m x l, Phng m vng trn. 310 Cc loi phng m A) Phng m trung chuyn aAMread(f,a);Gi tr binc im:- Vn nng,- H s song song cao,- Tn b nh v thi gian chuyn thng tin trong b nh.311 Cc loi phng m B) Phng m x l: aAMread(f,a);a ch bin trong phng mc im:- Km vn nng,- H s song song thp,- Khng tn b nh v thi gian chuyn thng tin trong b nh.312 Cc loi phng m C) Phng m vng trn: thng p dng cho cc h QT CSDL. X LC GHI313 3 - SPOOL SPOOL Simultaneuos Peripheral Opearations On-Line, Khng can thip vo CT ngi dng, Hai giai on: Thc hin: thay th thit v ngoi vi bng thit b trung gian (a cng), X l kt thc: Sau khi kt thc vic thc hin CT, a thng tin ra thit b yu cu.314 SPOOL m bo song song gia x l mt CT vi trao i vo ra ca CT khc. Chng trnhUSERSDISKOSThc hin chng trnhX l kt thc(min ph)

315 SPOOL Gii phng h thng khi s rng buc v s lng thit b, Khai thc thit b ngoi vi ti u, K thut lp trnh hiu qu. H thng cung cp cc phng tin ngi dng to SPOOL, Ai to SPOOL ngi x l kt thc. 316

Giai on thc hin: vi mi php trao i vo ra h thng to 2 CT knh: CT knh I theo thit b yu cu, CT knh II phc v ghi CT knh I ra thit b trung gian, X l kt thc: c CT knh lu v chuyn giao cho knh. Nh vy, mi thit b s dng file CT knh. 317 4 H THNG QUN L FILES - CSDL qun l files, H thng qun l files - H QT CSDL. H thng truy nhp vt l (truy nhp c s)H thng truy nhp l gc318 R1R2R3R4S1S2S3File ca UserFile lu tr trn a512 B512 B512 B300 B300 B300 B300 B300 B300 B319 H QT CSDLQun l filesAMTruy nhp l gcTruy nhp c sPhp trao i vo/raThit b vo/ra- Giao din tt,- Kch thc ln- c th tng h thng- C cng c cho php - C s: Lnh Macro,- Nn cao- Vn nngAPIUSERHTHNGTBK thut320 QUN L FILE TRONG WINDOWS Mc ch: Minh ho nguyn l bng tham s iu khin, Tnh k tha v thch nghi, C ch bo v, Cch th hin mt s ch qun l b nh (chng tip theo). 321 T CHC THNG TIN TRN A T Track111222333Sectoru t322 CC KHI NIM C BN Sector: nh s t 1, S Sector/track Constant, H s an xen (Interleave) nguyn t cng nhau vi s sector/track, Kch thc 1 sector: 128B 256B 512B 1KB 323 Cylinder: 0,1,2, . . . u t (Header): 0, 1, 2, . . . Cluster: Nhm sectors lin tip lgic, n v phn phi cho ngi dng, nh s: 2, 3, 4, . . . Kch thc: 1, 2, 4, 8, 16, 32, 64 (S), a ch vt l:(H, S, Cyl), a ch tuyt i: 0, 1, 2, . . . CC KHI NIM C BN 0 1 2 3 4 . . . . . . . . .324 CU TRC THNG TIN TRN A T MB BS FAT1 FAT2 ROOT FILESVng h thng (System Area)FAT16MB BS FAT1Vng h thng (System Area)FAT32FAT2ROOTFILES0E0E24 2416161C1C112C325 BOOT SECTOR c thCh k (Signature)Nh nhau vi mi a cho mi loi OSChng trnh mi(Boot Strap Loader)Tham s55AA326 BOOT SECTOR SttOffs L (Byte) Ngha 103Lnh JMP(EB xx 90) 238Tn h thng Format a 3B2Kch thc Sector 4D1Sec/Cluster 5E2 a ch tuyt i FAT1 trong a l gc 610H 1S lng bng FAT 7112FAT16: S phn t e ROOT FAT32: 00 00 8132E sect/Disk (32MB) hoc 015244E Sec / FAT 16282 Flags 172A2 Version 182C4 a ch ROOT (Cluster) 328

19302 Inf 20322 a ch lu BS 21341210 D tr (00...00) 22401 a ch a ( 80 C:) 23411 00 24421 29 BIOS m rng 25434 Serial Number 26471110Volume Name 27528 FAT32329 Boot Sector FAT 16 15241 a ch a ( 80 C:) 16251 00 17261 29 BIOS m rng 18274 Serial Number 192B1110Volume Name 20368 FAT16330 V d EB 58 90 4D 53 57 49 4E 34 2E 31 00 02 08 2D 00 02 00 00 00 00 F8 00 00 3F 00 40 00 3F 00 00 00 41 0C 34 00 03 0D 00 00 00 00 00 00 02 00 00 00 01 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00 80 00 29 D1 09 47 32 20 20 20 20 20 20 20 20 20 20 20 46 41 54 33 32 20 20 20 FA 33 C9 8E 41 BC 331 TH MC ng vai tr mc lc tra cu, tm kim, Mi h thng u phi c vi nhng tn khc nhau (Catalog, Directory, Folder,. . .), Bao gm: Th mc gc (ROOT) + Th mc con, Cc h thng ca Microsoft v OS IBM cu trc cy, UNIX - cu trc phn cp, Th mc = {Phn t}, mi phn t: 3210 B Phn t file, Th mc con v ROOT: File c cu trc. 332 Cu trc phn t th mc tn ngn (Phn t 8.3) SttOffsL ngha 108Tn (Name) 283Phn m rng (Extention) 3B1Thuc tnh (Attribute) 4C2Thi im to file 5E 2Ngy to file 610H 2Ngy truy nhp gn nht 712100 (Cho NT) 8131S 0.1 ca thi im to file 333 Phn t 8.3 91422 bytes cao ca cluster xut pht 10162Thi im cp nht cui cng 11182Ngy cp nht cui cng 121A22 bytes thp ca cluster xut pht 131C4Kch thc file (Byte) 334 Phn t 8.3 Byte s 0: Vai tr c bit. 00 Cha s dng, phn t cha s dng u tin - du hiu kt thc th mc, E5 (o) b xo, 05 Tn bt u bng k t o, 2E 20 (. ) Phn t th I ca th mc con, 2E 2E (..) Phn t th II ca th mc con xxxxxxxx00335 ......336 5 bitsGi6 bitsPht5 bits2 GiyTimex x x x x x x x x x x x x x x x7 bitsNm - 19804 bitsThng5 bitsNgyDatex x x x x x x x x x x x x x x x1998 181999 192000 202001 21D tr thi gian:1980 + 27-1 = 2107SystemThuc tnh0Xx0Xx32Ax16Dx 8Vx 4Sx 2Hx 1RxRead OnlyHiddenVol. NameDirectoryArchiveReserved337 Tn di Khng qu 255 k t, Unicode, H thng phn bit theo 66 k t u tin, Lu tr theo cch a vo, Nhn dng: a v ch hoa. Phn t tn di nPhn t tn di n-1Phn t tn di 1. . .Phn t 8.3Lu tr tn di338 Cu trc phn t tn di SttOffsL ngha 101S th t i (64+i) 211010 5 k t C1 C5 3B1Thuc tnh (00001111B) 4C100 du hiu phn t tn di5D1EK phn t 8.3 6E1210 C6 C11

71A200 00 81C4C12 C13

339 File Allocation Table (FAT) Chc nng: Qun l b nh phn phi cho tng file, Qun l b nh t do trn a, Qun l b nh km cht lng. FAT = {phn t} Phn t: nh s:0, 1, 2, . . . Tphn t s 2: phn t Cluster 340 Phn t12 bits 16 bits 32 bitsFAT 16FAT 32Phn t 0:FxxFFF8 FFFFFFF8 Phn t 1: FFF xx11FF8 0xx11FFFFF8Bit ShutdownBit DiskerrorBit ShutdownBit Diskerror341 FAT Bit Shutdown = 1 Ra khi h thng ng cch Bit Diskerror = 1 khng c li truy nhp a ln truy nhp cui cng. T phn t 2 tr i: Gi tr 0 Cluster t do, FF7 (FFF7, 0FFFFFF7) Bad cluster, Cc gi tr khc phn phi, Cc phn t tng ng nhng Clusters ca mt file - to thnh mt danh sch mc ni, EOC (End of Cluster Chain) FFF (FFFF, FFFFFFFF). 342 FF0FFFFF05FFF4937801234567896 9 8 7 3 5 4DISKCCCIIIRAMCluster xut phtFAT343 MASTER BOOT 55AAChng trnh nhn bit cu trc(Master Boot Record - MBR)c thCh k (Signature)Bng phn vngNh nhau vi mi a cho mi loi OSFDISK/MBR344 Nguyn tc khai thc HD:Chia HD thnh cc phn, mi phn c kch thc c nh, Mi phn s dng nh mt a t c lp: a l gic ( Logical Volume). OS cho php to cc a kch thc ng trong mi a l gic. MASTER BOOT 345 Cu trc bng phn vng Bng phn vng bt u t a ch 1BEH, Bng phn vng = {4 phn t}, Mi phn t s dng a l gic, Tn ti c ch cho php to nhiu hn 4 a l gc trn mt a vt l.a ch vt l ua ch vt l cuia ch tuyt i uTng s Sectors4 Bytes4 Bytes 4 Bytes 4 Bytes346 Cu trc phn t bng phn vng a ch vt l ua ch vt l cuia ch tuyt i uTng s Sectors4 Bytes4 Bytes 4 Bytes 4 BytesSYS H S Cylx x x x x x x x x x x x x x x x

6 bits Sector2810 bits CylinderType H S Cylx x x x x x x x x x x x x x x x6 bits Sector2810 bits Cylinder00 Cm truy nhp, 0B FAT32 ( s 2047 GB)01 DOS12, 0C ~ 0B, ch LBA,04 DOS16, 0E ~ 06, ch LBA,06 BIGDOS, 0F ~ 05, ch LBA,05 M rng (Extended)347 Bng phn vng 80 01 01 00 0B 3F FF 4D 3F 00 00 00 41 0C 34 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55AA 80010100 010511BF 11000000 6F4C0000 000001C0 5105511F 804C0000 40260000 00004120 510551DF C0720000 804C0000 000041E0 5105D132 40BF0000 12870000 55AA 348 Truy nhp Boot Sector Dng cc hm API, Chng trnh c v a ra mn hnh ni dung BS ca a mm A: (Hexa v ASCII): Program R_BS_A; Uses Crt, Dos; Const s16: string[16]=0123456789ABCDEF; VarB: array[0..511] of char; reg: registers; i,j,k: integer;c: char; BEGIN clrscr; fillchar(b,sizeof(b),0); writeln(Cho dia vao o A: va bam phim bat ky.); c:=readkey; 349 I := 0; Repeat with reg do begin dl := 0; { 0 -> A:, 128 -> C:} dh := 0; {u t} cl := 1; {Sector} ch := 0; {Cylinder} al := 1; {So Sectors can doc} ah := 2; {2 -> Read; 3 -> Write;. . .} es := seg(b); bx := ofs(b) end; 350 intr($13,reg); inc(i) Until i = 2; for i := 0 to 511 do begin j := b[i] sh