CNG N TP MN H IU HNH Bi 1: Tng quan v h iu hnh. Cu 1: Khi nim, chc nng ca HH. - L h chng trnh hot ng gia ngi s dng vi phn cng my tnh. -Chc nng: + To 1 my o tng i c lp vi phn cng, gip ngi s dng my tnh d dng hn. + Qun l - s dng ti nguyn hiu qu, an ton hn. Cu 2: Ngi s dng Cc chng trnh ng dng Cc tin ch(compilers, editors) H iu hnh Ngn ng my tnh Kin trc vi m Cc thit b vt l

Cu 3: HH Windows XP thuc loi no H iu hnh a nhim (Multitasking) Cu 4: V d v 2 my o c ci t trn mt PC vt l ( kin c nhn) - V d: PC ci t 2 HH Windows XP v Ubuntu 11.10. Bi 2: Tin trnh v tiu trnh. Cu 1: Khi nim - Tin trnh(process): + L mt chng trnh ang c thc thi, s hu mt ng cnh gm: khng gian a ch, mt con tr lnh, tp cc thanh ghi v stack. + Tin trnh c th cn n mt s ti nguyn nh CPU, b nh, cc tp tin v thit b nhp xut. - Tiu trnh: nu chng trnh c vit theo mt gii thut tun t th tin trnh ng vi n ch cha mt lung thi hnh lnh gi l tiu trnh thread, tun t thc hin t im bt u im kt thc chng trnh. Cu 2: Cc nhu cu dn n vic x l ng hnh cc tin trnh. - Tng hiu sut s dng CPU. - Tng tc x l. - Ngi s dng mun thc hin cng lc nhiu vic. Cu 3: V d chng t li ch ca vic x l ng hnh ( kin c nhn). - V d: ngi dng s dng hh Windows XP c th cng mt lc: nghe nhc, lt web, son tho vn bn, lp trnh

Cu 4: Xem danh sch cc tin trnh ang hot ng trn Windows XP + Trn mn hnh Desktop bm t hp phm Ctrl+Alt+Del -> Windows Task Manager -> chn th Processes. + Chut phi thanh tc v (TaskBar) chn Start Task Manager -> chn th Proccesses. Bi 3: Qun l tin trnh. Cu 1: Cc trng thi ca tin trnh. - New: tin trnh mi c to ra. - Running: tin trnh ang c thc thi. - Waiting (block): tin trnh ch mt s kin no xy ra (I/O, cp pht ti nguyn, nhn tn hiu ). - Ready: tin trnh sn sang thc thi nu c cp pht CPU. - Terminated: tin trnh kt thc, b nh cp pht cho tin trnh c gii phng.

Cu 2 : Cc thao tc qun l tin trnh. - To lp tin trnh (create process). - Kt thc tin trnh (terminate process). - Thay i trng thi tin trnh (change process state). - Thay i u tin tin trnh. Cu 3: S trng thi v cc thao tc chuyn sang trng thi tin trnh.new admited interrupted ready running exit terminated

Scheduler dispatch I/O or event completion waiting I/O or event wait

Cu 4: Mc tiu ca vic iu phi tin trnh. - m bo s cng bng gia cc tin trnh. - Tng hiu qu s dng CPU. - Gim thiu thi gian lu li h thng. - Tng ti a thng lng.

Cu 5: S t chc iu phi tin trnh trong trng hp cc tin trnh tham chiu ti 3 ti nguyn .Cp resourceCp CPU

Kt thc

Ready List

CPU

Time-out or ininterrupt

Cp resource

Waiting list for resources 1 Waiting list for resources 2 Waiting list for resources 3

blocked

Cp resource

blocked

Cp resource

blocked

Cu 6: Chin lc iu phi tin trnh (khng v s ) - n trc phc v trc (FCFS, FIFO). - Xoay vng (round robin). - Cn c vo u tin (priority-scheduling). - u tin cng vic t thi gian (shortest-job-first). - Chia thnh nhiu cp u tin. - Chn ngu nhin (lottery). Cu 7: B!!! Bi 4: Lin lc v ng b ha.

Cu 1: Cc c ch lien lc gia cc tin trnh. - Signal. - Message. - Pipe. - Socket.

- Shared Memory.

Cu 2: Giao thc TCP/IP thuc c ch Socket (khp ni) nhng c th hin bng port.

My Asocket socket

My B

Port

Mi ni

H thng mng

Cu 3: V d v tnh hung xung t. - V d v h thng bn v my bay online:

i l bn v P1 i l bn v P2

Ngn hng B Hng hng khng A

+ Quy trnh bn v ti i l: B1: hi A s ch cn trng SCA: N:=SCA B2: if N=0 then dng else i tip B3: chuyn tin mua v T vo ti khon TKA ca A ti B: TKA:=TKA+T B4: in ha n cho khch hng B5: tr N i 1 v yu cu A ghi vo SCA: SCA:=N-1 + Hai i l cng bn v:Time 0 1 2 3 4 5 6 P1 B1: N:=SCA B2: (N=1) B3: B4: B5: SCA:=N-1 P2 A: SCA SCA=1

+ Nguyn nhn sai: P1 v P2 cng truy xut vo SCA.

B1: N:=SCA B2: (N=1) B3: B4: B5: SCA:=N-1

SCA=0 SCA=0

SAI

Cu 4: Khi nim min gng (critical section), cc yu cu gii quyt tt vn ng b ha. - KN: l on chng trnh trong c kh nng xy ra cc sai st khi truy xut trn ti nguyn chung. - Cc yu cu: + Loi tr ln nhau: khng th c 2 tin trnh cng lc trong min gng. + Tin : ch nhng tin trnh ang khng thc thi mi c th tham gia vo vic quyt nh tin trnh tip theo i vo min gng. + Ch i c gii hn: gii hn s ln cc tin trnh khc c php i vo min gng sau khi mt tin trnh thc hin yu cu i vo min gng ca n v trc khi yu cu c tha mn. Bi 5: Cc gii php ng b ha. Cu 1: Gii php bin kha trong trng hp c 2 tin trnh P0 v P1 c yu cu vo min gng. Gii thch v sao gii php ny khng p ng c yu cu Loi tr ln nhau? - Gii php: dng 1 bin chung (lock) cho cc tin trnh xc nh tnh trng c vo on gng hay khng (0:c ; 1:khng c ). Lock=k: c k tin trnh ang trong on gng. Do{ While(Lock ==1); Lock=1; Lock=0; }while(TRUE); - Gii thch: v vn c th c nhiu tin trnh cng vo on gng. Cu 2: Gii php Peterson trong trng hp ch c 2 tin trinh P0 v P1 c yu cu vo min gng. -Gii php: dng 2 bin int turn; boolean flag[2]; Trong : turn=1 : n lt Pi c quyn vo min gng. flag[i]=true : Pi c yu cu vo min gng.

Do{ flag[i]=TRUE; turn =1-i; while (flag[1-i] && (turn ==1-i); flag[i]=FALSE; }while(TRUE); Cu 3: Gii php Semaphore. + Dijkstra xut nm 1965. + ng vi mi ti nguyn gng CR, to 1 bin nguyn S vi gi tr khi u l 1 v 1 waiting list F lu cc tin trnh ch c cp quyn truy xut CR. +Trong hh, thit lp 2 th tc nguyn t Down(P,S,F) v Up(S,F), P l tin trnh mun truy xut CR. Procedure Up(S,F); Begin S:=S+1; If S chng trnh chy nhanh hn. Cu 2: Khi Nim li trang(page fault), cc bc x l, v s x l. - KN: l vic truy xut n 1 trang ang b nh ph (c nh du invalid). C ch phn cng s pht sinh mt ngt bo cho HH. - Cc bc x l: + Kim tra tham chiu xem vic truy cp b nh l hp l hay khng. + Nu tham chiu khng hp l th kt thc tin trnh. Nu hp l nhng trang cha np vo b nh th chuyn bc tip theo. + Tim khung trng (t danh sch khung trng). + Nu c khung trng th c trang vo khung trng. Khng c khung trng th thay th trang. + Cp nht bng bn trong tin trnh v bng trang hin th trang by gi trong b nh. + Khi ng li ch th b ngt bi li trang. -S x l:

3

Page is on backing stone

Operation System

2

reference 1 Load M i6

trap

Restart instruction5

Free frame4

Reset page table Physical memory

Bring in missing page

Cu 3: Cng thc tnh thi gian trung bnh truy xut cho 1 truy xut trang. V sao phi gim thiu xc sut xy ra li trang? Trong : p: xc sut li trang. (1-p)*m + p*t m : thi gian truy xut nu khng li. t : thi gian x l li. - L do phi gim p : m nh hn rt nhiu so vi t. Cu 4 : trnh by gii thut ti u cho vic thay th trang. V sao gii thut ny khng c p dng trong thc t ? - tng : Thay th trang s lu c s dng nht trong tng lai. -Nhn xt : +L gii thut c t l li trang thp nht. +Khng thc t, v kh bit trang no s lu s dng nht. +Khng gp nghch l Belady.

Cu 5 :Gii thut LRU cho vic thay th trang. - tng : thay th trang khng c s dng lu nht trong qu kh. - Nhn xt : + Dng qu kh d on tng lai : lu c s dng nht trong tng lai. + Khng gp nghch l Belady. - Ci t : s dng c ch b m hoc c ch stack. Cu 6 : b !!!