ls chapters 123 new

8/14/2019 LS Chapters 123 New

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,

/ ,

&

2004


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! ! , . !

76


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1 ............................................................................................................ 8 1.1 & ............................... 9 1.2 .....................................................................10 1.3 ...................................................................................................................12

1.3.1 (Buffering)....................................................................13 1.3.2 (Spooling) ........................................................................................................13 1.3.3 - (Multiprogramming)........................................................................14 1.3.4 (Time Sharing)...................................................................................15

1.4 .................................................................................................................................16 1.4.1 / .......................................................................................................................16 1.4.2 ...................................................................................................................17 1.4.3 .................................................................................17

1.5 ..................................................................18

1.6

&

..................................21 1.7 .........................................................................................................21 1.8 ..........................................24

1.8.1 ............................................................................................24 1.8.2 ..........................................................................................................24 1.8.3 ..................................................................................................................................25 1.8.4 .................................................................................................................27 1.8.5 goto.........................................................................................................................28 1.8.6 ..................................................................................................................28 1.8.7 Typedef ..................................................................................................................................29 1.8.8 ...........................................................................................................................29 1.8.9 ..........................................................................................................................29

2 ............................30 2.1 .........................................................................................................31 2.2 ..........................................................................................................31 2.3 .............................................................................................32 2.4 .....................................................................................................33 2.5 ...................................................................................................................................34 2.6 ................................................................................................................39 2.7 .........................................................................................43

2.7.1 (First Come First Served, FCFS) .............43 2.7.2 (Round Robin, RR) ........................................................................................44 2.7.3 (Priority).....................................................................................................45 2.7.4 ..............................................................46

3 & ..........................58

3.1 ........................................................................................59 3.2 ........................................................................................................69 3.3 .......................................................................73 3.4 ........................................................................................75 3.5 ......................................................................................82

3.5.1 ......................................................................................83 3.5.2 Peterson..................................................................................................................90

3.6 ................................................................................................................................99 3.7 ....................................................................105

3.7.1 ................................................................................................................105 3.7.2 ( 6, , 2003).............113 3.7.3 ( 3 , , 2001) ..............................117 3.7.4 - ........................................................................119


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3.7.5 ...................................................................................................121 3.7.6 ..........................................................................................................125

3.8 ................................................125

3.9 ..................................................................................................................133 3.9.1 Lamport (Bakery Algorithm)................................................................................133 3.9.2 Dekker ..................................................................................................................135 3.9.3 ...........................................................................................................................136 3.9.4 ....................................................................................................................139


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1: ............................................... 9 2: ............................................................................................12 3: .....18 4: . ..........................................................................................32 5: PCB ..............................................................................................................33 6: . ................................................................................................................37 7: . ......................................................................................................40 8: . ...............................................41 9:

.............................................................................................................................................43 10: RR........................................................52 11: GANNT 6.

.............................................................................................................................................................54 12: 1 ..............................................................61 13: 1 : .......62 14: 2 ..............................................................63 15: . .......................................................................64 16: TALLY . ...68 17: ......................................................................................70 18: 1000 500....72 19: . ........................................74 20: . ..........................................75 21: TEST &S ET()...............................................................................................................76 22: TEST &S ET()...76 23: 0 1 TEST &S ET()

...............................................................77 24: TEST &S ET()

...........................................................................................................................78 25: DEPOSIT ()................................................................................................79 26: WITHDRAW ()...........................................................................................79 27: 1

TEST &S ET(). .........................................................................................................80 28: FETCH &A DD ()...........................................................................................................81 29: SWAP ().......................................................................................................................81 30: RMW()......................................................................................................................82 31:

......................................................................................................................................83 32: 1

...........................................................................................................................84 33:

......................................................................................................................................84 34: 2 .....85 35: ( )

. .......................................................................................86 36: 3 ...87 37:

......................................................................................................87 38: PETERSON . ..............................................................................................................90 39:

......................................................................................................92 40:

......................................................................................................................................93


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41: 5 ...........................................................................................................................95

42: PETERSON ................................................95

43: PETERSON ......................................................................................................96 44:

......................................................................................................................................97 45:

......................................................................................................................................97 46: . 98 47:

............................................................................................................................................98 48: UP () DOWN () ........................................100 49: . ....................................100 50: .............................................................................101 51: . ...............................................................102 52:

TEST &S ET() ...........................................104 53: . ..................107 54: - . .......................................................109 55: - . .................................110 56: - ........................................................110 57: - . ....................................................................112 58: PING -PONG ................................................................................................................................113 59: ..114 60: ............................................................114 61: . ..................................115 62: .................................116 63: . ..................................................117 64: ....................118 65: . .........................................................................................119 66: - . .....................119 67: - .....................................................................120 68: . ........................................................................121 69: 44. ..............123 70:

45...................................................................................................................125 71: HANSEN . ...........................................................................................126 72: DEPOSIT () WITHDRAW ()

HANSEN . ...................................................................................................... 127 73: . ......................................................127 74:

( 60)........................................................................................129 75:

( 61)...............................................129 76:

( 62)...............................................130 77: 76

. .............................................................................................................................131 78: -

...................................................................................................131 79: -

. ...................................................................................................................................132 80: . .........................................................................................134 81: DEKKER . ...............................................................................................................135 82: TEST &S ET()...........137


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83: - . ................................................139 84: SEM _DOWN () GSEM _UP ()...............................141 85: . ................................................141

86: . ....................................................................................................................................143


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1


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1

9

1.1 &

() (user interface) (hardware) . (1) , (2) ,(3) , (4) . 1.

1: .

, ( CPU), / ( / ) . , , , , , ., , , .

. (. ., , , , , , / , .) (. ., , , , .). , (. ., ).

. , .

1 2 3

&


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1

10

. , . . .

. . , .

, , . , , . , .

, . , .

1.2

( ) . . . , . . (1 ) . . .

(system clock)

. .

. 32 64 bit. . (Program Counter, PC). .

chip (


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1

11

), . , bytes. , , . , . ( ). , . . , .

( ) (system bus).

(. ., ).

. . , . . , . 2.

, . ., , , , . . . ( ) ( ). , (main memory). , . ( ). , ( , ). . .

, . . , . , . 2. , ( ).


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1

12

2:

( ) , . , ( ). , . , ( - ). , . , , .

1.3

. ( 100%). , , , .

/ . / . / , (. ., ). . / . .

( , , )

( )


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1

13

1.3.1 (Buffering)

. . / , ( ) (buffer) , . , / . . . / . , / ,.

bytes. . / . . / ( ). , / . , . 2.

/ . . . ., , ( / ), ( / ). ,

/ . , , / . ( ) .

1.3.2 (Spooling) (Spooling Simultaneous Peripheral Operation On Line) . .


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1

14

, / . , / .

, / (offline). . ., . . , . ., . / . , /

. / .

. .

1.3.3 - (Multiprogramming) 100% . ,

- . . / , . ( ). , . / , , . .

. . , - ( ), .

. , . , . ( ).


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1

15

. .

1.3.4 (Time Sharing) (interactive) online . . , , , , . / , , , , , ..

, , . (switching) . , , . , , .

,

. , . , , ( -) .

:

/ . (. .,

) .

, . ( , batch systems) . ( ) , .

. , ( )


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1

16

. , .

1.4

. . , (

). , , , ( / ) , . , .

1.4.1 / / , . , , . / . , (supervisor mode), (usermode), . , bit. bit 0 , ( ). / ,

. . (privileged instructions).

/ , . . , / , ,


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1

17

. , . .

, . , , . , , . , /

. / , , . , - ( ). , , .

1.4.2 , . . . , , .

,

.

1.4.3 . ( ), , . , , .


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1

18

. , . , . , . ., , , .. .

, , (base register) (limitregister). ,

, . , . ( ) . , , . , . , (trap). . 3. ,

.

3: .

1.5

. 2. . :

( , ).

+

< <


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1

19

, . .

.

. , , , , . , , , , . , ,

, . , . ( , , ). , . 2 3.

. :

, .

. ,

, .

4.

, , . , .

. (. ., ). , . ., , CDs, , . . , . , , , ,


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1

20

, , ..

/ . , / . , , (device driver). / . , , .

. , . . , .

. , , . . Windows Windows. , . .

. / . :

. . .

. . / . , ..

(assembly). ( , ).


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1

21

1.6 &

. , . , . , ( ), ( , ,

), , ..

. . . , .

.

. , . ., ( ), ( ), ..

1.7

1 ( 1, 4 . 2001-2002)

1. :

)

)

)

2. (i, ii iii) . .

) .

) .


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1

22

) .

) .

3. ;

) .

) .

)

)

)

) / .

1. :

) .

/ .

.

.

) .

. . ,

.

) .

.

2. , . , . , . . , , ,


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1

23

, ( ). , :

. , .

. , .

.

, . . .

. ( . editor, help browser, , ), .

3.

.)

( ).

) .

) / , , .

) . , .

) , . .


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1

24

) / / .

1.8

. . .

1.8.1

:

int num;

num num . , boolean. boolean flag; flag boolean. boolean , TRUE FALSE. boolean , 0 FALSE TRUE.

. . .,

int num = 5;

num, num 5.

1.8.2 . . .,

num = 1;

1 num.

num = num +1;

num 1.

num++;

num += 1;


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1

25

+ , , * / . +.

1.8.3 repeat . (repeat, begin, end, until), until, :

repeatbegin

;end

until < >;

begin, end repeat. repeat . , until . , . , repeat ( until). boolean , == , != ( ), , , .

while.while (< >) do

begin;

end

while TRUE, . while . , . , .. .

repeat while , . ., ,

, . ., repeat while. ( ).

repeat:

repeatbegin

;end

forever;


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1

26

( , repeat ). repeat:

repeatbegin

;end

until FALSE;

FALSE ( ), repeat repeat .

while:

while (TRUE) dobegin

;end

H repeat, while . , TRUE. , FALSE. , not < >. , TRUE, 0 FALSE .

, begin, end .

, repeat, while:

repeat noop; until < >;

while (< >) do noop;

noop ( ). , , . , . , repeat while (

), TRUE FALSE, .

1

:

int num = 0;

while (num < 3)num = num+1;

print num;


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27

. num 0. , (num < 3) TRUE while, num 1. , . 1 < 3 TRUE. , num 2. TRUE. num 3 . , FALSE ( 3 < 3). , while , print num;. 3 .

, repeat while;

int num = 0;

repeatnum = num + 1

until (num >= 3);print num;

.

repeat, while. while TRUE, repeat TRUE ( FALSE). repeat, while , . ,

repeat , while ( , , , while FALSE, ).

, , for,break, continue, .. ( ).

1.8.4 if . :

if (< >) thenbegin

end

, ( ) if. , . if repeat while .

if .


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28

if else :

if (< >) thenbegin;

endelse

begin;

end

. TRUE 1, 2.

1.8.5 goto goto , goto :

goto part1;

, part1. part1, :.

part1: num = num +1;

goto part1. , goto .

1.8.6

int array[4];

4 array. array 4 . array[0], o array[1], array[2], 4 array[3]. , n , k- , 0< k n, array[k-1].

(structure) . ( , ). . :

struct 2fieldsbegin

int a;boolean flag;

end


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29

2fields , a boolean flag. 2fields :

struct 2fields b;

b 2fields. b , b.a boolean b.flag.

1.8.7 Typedef typedef . 2fields. :

typedef struct 2fields 2FIELDS;

2FIELDS struct2fields. , :

2FIELDS b;

b 2fields.

, :

typedef int boolean;

boolean int .

1.8.8 . . 3 .

1.8.9 3 ( ).

/* */ , .


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31

2.1

. ( ).

, . , . . , (

), , . . . , , , , . , , , ( , , ). .

, . , . , , .

2.2

. , ,

. . , , , (. ., / ) . , : , .

4 . . , . , / , ( / ). ,


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32

/ , . , , , . , . .

4: .

2.3

, . ( ). , ( ) ,

, . , , . ( , , . , ).

(Process Control Block, PCB).


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33

PCB. PCB :

. . . . ,

.

, .

(. ., , / , ).

PCB 5.

... ( )

5: PCB .

2.4

:

. . (foreground) , (background). (daemons). , . . , .


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34

.

. , , . ., . , PCB .

- . . ., / . . .

. ,

. . , .

2.5

. :

. .

. , . ., .

, , ..

/ . / , / , , , .

, . ., restart INT.

( ). , . .

2

.

int b = 3, c = 4, p = 5;int tmp, flag = 0;


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2

35

tmp = 1;while (p > 0)

begin

if (flag == 0)tmp = tmp * b;

elsetmp = tmp * c;

flag = 1 flag;p = p - 1;

endprint tmp;

. ( ) b*c*b*c*b.

, . , 28 ( ).

1. tmp = 12. while ( TRUE)3. if ( TRUE)4. tmp = 1 * 3 = 35. flag = 16. p = 47. while ( TRUE)8. if ( FALSE)9. tmp = 3 * 4 = 1210. flag = 011. p = 312. while ( TRUE)13. if ( TRUE)14. tmp = 12 * 3 = 3615. flag = 116. p = 217. while ( TRUE)18. if ( FALSE)19. tmp = 36 * 4 = 14420. flag = 021. p = 122. while ( TRUE)23. if ( TRUE)24. tmp = 144 * 3 = 432


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2

36

25. flag = 126. p = 0

27. while ( FALSE)28. print 432

, . , , , .

. . ,

. ., if else while. while 2 27. 25 while. 2 3, 3 4, .. ., 26 27. , . . ., 17, , , if else.

, while TRUE, , if else ( if else 18). , , while, if. . ., 18. if else, KME.

, . (interrupt handlers). . , :

( PCB ).

.

, .


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2

37

, .

6

.

6: .

3

( -) 2. ( , . ., while if else). , . :

2012 b = 3;2016 c = 4;2020 p = 5;2024 flag = 0;2028 tmp = 1;2032 label1:2036 if (p


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38

, 2 ( 2). ( 2).

2064, . :

PC (program counter) = 2064, tmp = 3, flag = 0, p = 5, b = 3, c = 4.

, . ,

PCB . , . PCB , , . , . , .

, 2072. :

PC = 2072 , tmp = 12, flag = 0, p = 3 , b = 3, c = 4.

PC ( ) . PCB , .

4 ( , , , -11: )

. count-processes (). 100 ( 100 count-processes()) , . .

( , . ., while, repeat, for, .)

1004 print Start;


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39

1008 i = 0;1012 old_proc = 0;1016 label1:

1020 if (i == 100)1024 goto label2;1028 new_proc = count_processes ();1032 if (new_proc > old_proc)1036 print Up;1040 else if (old_proc > new_proc)1044 print Down;1048 print new_proc;1052 old_proc = new_proc;1056 i ++;1060 goto label1:1064 label2:

1068 print End; count_processes 37, 41, 21, .

1004 ( ) 1032. 1036, . , , . , PCB :

= 1036, i = 0, new_proc = 37, old_proc = 0 , , 1052. PCB :

= 1052 , i = 0, new_proc = 37, old_proc = 0

1056,

= 1056 , i = 0, new_proc = 37, old_proc = 37

. , , .

2.6

(ready queue) . PCB


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40

. 5 , , , 7.

7: .

. , PCB . , FIFO .

. :

/ . . .

( ) . , / . PCB / .

( / ), ( ), . , PCB / . , , , PCB . 8 .

, - . - , , (. ., / ) .

PCB A PCB B PCB PCB PCB


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42

. t1 t2, o = t 2 t 1 ( t2-t1 ). . n p1, ..., p n,

= ( 1 + 2 + ... + n) / n ,

1, ..., n p1, ..., p n, .

. , t1, t2

d , XA = t 2t1d. n p1, ..., p n,

= ( 1 + 2 + ... + n) / n ,

1, ..., n p1, ..., p n, .

, . , , ,

. . ( , , ), .

, ( ) . , ,

. . . . , . 9 .


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43

9: .

2.7

.

2.7.1 (First Come First Served, FCFS) . FIFO. . . . FCFS - .

/ . . .

FCFS . ( , , ). ( ) ( ) ( ).

, , 100 / . 1 / . , , 100 . , , .


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44

. . . , , , / , . , / . , 100 . , , . . , , . ., . .

2.7.2 (Round Robin, RR) RR FCFS. FCFS, RR FIFO . , . , RR . . / , RR . RR .

RR , , ( ), . , RR . RR , ( ).

. , . , , 10 . 1 sec,


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45

10 . . ( ) . . (process switch) (context switch) , , . , ( , ). , , .

2.7.3 (Priority) . . , . ( , .) , . . - , / , . , . , , .

. . , .

. . ., , , , .. .

, , , .

( ) . , . , .


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46

, , , . , . . . , , ( , , ). , .

(Shortest Job First, SJF),

. SJF . (Shortest RemainingTime First, SRTF). , , SRTF . , .

SJF . , ( ) . ( / ). . , ( ).

2.7.4 .

5

.

A 3 70 ms

B 1 10 ms

3 20 ms


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48

0 10 80 100 150 160

ms

. , . , , . ( . , , , . , , .

Gantt = 80 ms, = 160 ms, = 100ms, = 10 ms, = 150 ms. , = ( + + + + ) / 5 =(80+160+100+10+150) / 5 ms = 100 ms.

, = 10 ms, = 150 ms, = 80 ms, = 0 ms, = 100 ms. , = ( + + + + ) / 5 = (10+150+80+0+100) / 5 ms = 68ms.

3. SJF

0 10 20 40 90 160

ms

( ). , .


, = 90 ms, = 0 ms, = 20 ms, = 10 ms, = 40 ms. , = ( + + + + ) / 5 = (90+0+20+10+40) / 5 ms = 32 ms.

4. RR

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160


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49

ms

10 ms

.


, = (160-70) = 90 ms, = 10 ms, = (70-20) = 50 ms, = 30ms, = (140-50) = 90 ms. , = ( + + + + ) / 5 =(90+10+50+30+90) / 5 ms = 54 ms.

, SJF .

FCFS .

, , .. . , , = + ( + + ...+ )/5. , ( + + ... + )/5 . , .

( ), -

Priority . SJF SRTF ( Priority).

6

7 4 . 2003-04.

:

1 8

2 4

3 9

4 5

:1. FCFS


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50

2. SJF 3. SRTF

4. RR 2 0.

Gantt 11. , .

1. FCFS . , , , , . 1 Gantt 11 = (9-1) = 8 , = (13-2) = 11 , = (22-3) = 19 , = (27-4) = 23 . , = ( + + + ) / 4 =

(8+11+19+23) / 4 = 15,25 . , = (9-8-1) = 0 , = (13-4-2) = 7 , = (22-9-3) = 10 , = (27-5-4) = 18 . , = ( + + + ) / 4 = (0+7+10+18) / 4 = 8,75 .

2. SJF , 1. 9, , . SJF , . .

2 Gantt 11 = (9-1) = 8 , = (13-2) = 11 , = (27-3) = 24 , = (18-4) = 14 . , = ( + + + )

/ 4 = (8+11+24+14) / 4 = 14,25 .

, = (9-8-1) = 0 , = (13-4-2) = 7 , = (27-9-3) = 15 , = (18-5-4) = 9 . , = ( + + + ) / 4 = (0+7+15+9) / 4 = 7,75 .

SJF FCFS . , .

SJF , . , ( ).

3. SRTF 1. 2 , SRTF ( 7 ) ( 4 ) , . 3 SRTF


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. 7 , 3 9 . , . 4, . ( ) SRTF , . 6, , ( ).

3 Gantt 11 = (18-1) = 17 , = (6-2) = 4 , = (27-3) = 24 , = (11-4) = 7 . , = ( + + + ) / 4 = (17+4+24+7) / 4 = 13 .

, = (18-8-1) = 9 , = (6-4-2) = 0 , = (27-9-3) = 15 , = (11-5-4) = 2 . , = ( + + + ) / 4 = (9+0+15+2) / 4 = 6,5 .

4. RR . 0 , 1 . 2 . . , . , , , . . .

, , , , , . 10. i

i (i+1). i. , 4 , , , ( 4). 4 5.

1 . 2 . 3 . .


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. 4 . 14 15 15 ( 14). , , 22, 23 27, .

0 - - - -

1 - -

2 -

3 , -

4 , , -

5 - , , -6 - , , -

7 - , , -

8 - , , -

9 - , , -

10 - , , -

11 - , , -

12 - , , -

13 - , , -14 - , , -

15 - ,

16 - , -

17 - , -

18 - , -

19 - , -

20 - , -

21 - , -

22 -

23 - -

24 - - -

25 - - -

26 - - -

27 - - -

10: RR.


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. : SJF ( );, , SJF. ( ) . Gantt SJF .

3 ( 3, , . 2001-2002)

:

0 3

1 4

3 2

4 4

6 3

. , KME .

: Gantt . 6. :

0 -

... ... ... ...

.

4 ( 2 , 2002)

0 .


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57

3

1

2

1

1

1. RR 1 , . .

2. 4 . ( Gantt) . .

: () . (). , , ( , ,,,,). , , .


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3 &


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3 &

59

3.1

, .

2 2 . , , . ( , ).

28 2. , , , .. . , . . , ( ) . , . 12 ( ). 13. 13, . , ( ). 13 12 . 14.

. , ( ) . , , ( ). , - . . , , .

: tmp = 1 ( . 1)


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3 &

60

: tmp = 1 while if tmp = 1 * 3 = 3flag = 1p = 4 while if tmp = 3 * 4 = 12flag = 0p = 3 while

: while if tmp = 1 * 3 = 3

flag = 1p = 4 while if tmp = 3 * 4 = 12flag = 0p = 3 while if tmp = 12 * 3 = 36flag = 1p = 2

while if tmp = 36 * 4 = 144flag = 0

: if : p = 1

while if tmp = 144 * 3 = 432flag = 1p = 0

: tmp = 12 * 3 = 36

flag = 1p = 2 while if tmp = 36 * 4 = 144flag = 0p = 1 while if tmp = 144 * 3 = 432

: while: flag = 1

(. 1)(. 2)(. 3)(. 4)(. 5)(. 6)(. 7)(. 8)(. 9)(. 10)(. 11)(. 12)(. 2)(. 3)(. 4)

(. 5)(. 6)(. 7)(. 8)(. 9)(. 10)(. 11)(. 12)(. 13)(. 14)(. 15)(. 16)

(. 17)(. 18)(. 19)(. 20)(. 13)(. 21)(. 22)(. 23)(. 24)(. 25)(. 26)(. 14)

(. 15)(. 16)(. 17)(. 18)(. 19)(. 20)(. 21)(. 22)(. 23)(. 24)(. 27)(. 25)


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3 &

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p = 0 whileprint 432

: print 432

(. 26)(. 27)(. 28)(. 28)

12: 1

tmp = 1 while if tmp = 1 * 3 = 3flag = 1p = 4 while if tmp = 3 * 4 = 12flag = 0p = 3 while

if

tmp = 12 * 3 = 36flag = 1p = 2

(. 1)(. 2)(. 3)(. 4)(. 5)(. 6)(. 7)(. 8)(. 9)(. 10)(. 11)(. 12)

(. 13)

(. 14)(. 15)(. 16)

tmp = 1

while if tmp = 1 * 3 = 3flag = 1p = 4 while if tmp = 3 * 4 = 12flag = 0p = 3 while if tmp = 12 * 3 = 36flag = 1p = 2 while if tmp = 36 * 4 = 144flag = 0

p = 1 while if tmp = 144 * 3 = 432flag = 1p = 0

(. 1)

(. 2)(. 3)(. 4)(. 5)(. 6)(. 7)(. 8)(. 9)(. 10)(. 11)(. 12)(. 13)(. 14)(. 15)(. 16)(. 17)(. 18)(. 19)(. 20)

(. 21)(. 22)(. 23)(. 24)(. 25)(. 26)


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while if tmp = 36 * 4 = 144flag = 0p = 1 while if tmp = 144 * 3 = 432

flag = 1p = 0 whileprint 432

(. 17)(. 18)(. 19)(. 20)(. 21)(. 22)(. 23)(. 24)

(. 25)(. 26)(. 27)(. 28)

while

print 432

(. 27)

(. 28)

13: 1 :

tmp = 1

while

if

tmp = 1 * 3 = 3

flag = 1

p = 4

while

if

tmp = 3 * 4 = 12

flag = 0

p = 3

while if tmp = 12 * 3 = 36flag = 1p = 2 while if

(. 1)

(. 2)

(. 3)

(. 4)

(. 5)

(. 6)

(. 7)

(. 8)

(. 9)

(. 10)

(. 11)

(. 12)(. 13)(. 14)(. 15)(. 16)(. 17)(. 18)

tmp = 1

while

if

tmp = 1 * 3 = 3

flag = 1

p = 4

while

if

tmp = 3 * 4 = 12

flag = 0

p = 3

while

(. 1)

(. 2)

(. 3)

(. 4)

(. 5)

(. 6)

(. 7)

(. 8)

(. 9)

(. 10)

(. 11)

(. 12)


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tmp = 36 * 4 = 144flag = 0p = 1

while

if

tmp = 144 * 3 = 432flag = 1p = 0 whileprint 432

(. 19)(. 20)(. 21)

(. 22)

(. 23)

(. 24)(. 25)(. 26)(. 27)(. 28)

if tmp = 12 * 3 = 36flag = 1p = 2 while if tmp = 36 * 4 = 144flag = 0p = 1

while

if

tmp = 144 * 3 = 432flag = 1p = 0 while

print 432

(. 13)(. 14)(. 15)(. 16)(. 17)(. 18)(. 19)(. 20)(. 21)

(. 22)

(. 23)

(. 24)(. 25)(. 26)(. 27)

(. 28)

14: 2

( )

cobegin s 1; s 2; ... s n; coend

parbegin s 1; s 2; ... sn; parend

s1, s2, ..., sn . s1, s2, ..., sn .

7

:

shared int tally;

begintally := 0;cobegin

increase();increase();

coend


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end

increase() ( ).

; , cobegin coend , increase(). . tally (shared) . . . ( , increase() .)

tally . tally, .

8

increase() 7 :

void increase()int tmp, i; /* */ begin

tmp = tally;tmp = tmp+1;tally = tmp;

end , . 15 ( tmp , 15 , tmpA, tmpB, ):

A B

1. tmp = tally;2. tmp = tmp +1;3. tally = tmp ;

1. tmpB = tally;2. tmpB = tmpB +1;3. tally = tmpB;

15: .

tally, tally.

tally , 0;

, tally ( 1 2).


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65

:

tmp = tally;tmp = tmp +1;

tally = tmp ;

tmpB = tally;tmpB = tmpB +1;

tally = tmpB;

, tmpA tally ( 0). tmpA 1, tally, . , tmp tally (

tally 0). tmpA 1 . tmpA ( 1) tally . , tmpB ( 1) tally . , tally 1.

1 tally. , . ., ; - ;

9

increase() 7 :

void increase()int tmp, i; /* */ begin

for i=0 to 5 dobegin

tmp = tally;tmp = tmp+1;tally = tmp;

endend

, . for , tally, tally.

:

A B

for i = 1 to 5 do begin

for iB = 1 to 5 do begin


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1. tmp = tally;2. tmp = tmp +1;

3. tally = tmp ;end

1. tmpB = tally;2. tmpB = tmpB +1;

3. tally = tmpB;end

tmpA, tmpB, iA iB ( ) .

tally . , . ( ) tally 5. , , 5 tally tally 1 ( for). , , tally

10. tally, ( - ). , tally 5. , 13 14 tally .

5 tally. ,

tally. 2. tally 2 . . , ( tally 2).

:

tally 0.

A 0 tmpA B.

B tmpB 0. 4 B . tally 4. for B, A.

A , for. tmpA 0, tally 4,


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, ( 3) tally 1. 4 , B.

B . tally ( 1) tmpB. , tally 1 ( A ). B (4 tally) . B 2 3 , .

, tally 5. 2 3 B,

. tmpB 1, tally

5, 1 , tmpB 2 ( 2), tally 2 ( 3) .

tally 2.

( ) 16.

tmp = tally; /* tmpA 0 */

tmp = tmp +1; tally = tmp ; /* tally 1 */

tmp = tally; tmp = tmp +1; tally = tmp ; /* tally 2 */ tmp = tally; tmp = tmp +1; tally = tmp ;

/* tally 3 */ tmp = tally; tmp = tmp +1; tally = tmp ;

/* tally 4 */ tmp = tally; tmp = tmp +1; tally = tmp ;

/* tally 5 */

tmpB = tally; tmpB = tmpB +1; tally = tmpB; /* tally 1 */ tmpB = tally; tmpB = tmpB +1; tally = tmpB;

/* tally 2 */ tmpB = tally; tmpB = tmpB +1; tally = tmpB;

/* tally 3 */ tmpB = tally; tmpB = tmpB +1; tally = tmpB;

/* tally 4 */

tmpB = tally; /* tmpB 1 */

tmpB = tmpB +1; tally = tmpB;


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/* tally 2 */

16: tally.

:tmp = tally;tmp = tmp+1;tally = tmp;

:

tally = tally + 1;

H tally . tally = tally +1; tally. , tally , tally. , tally= tally +1; , , tmp = tally; tmp =tmp +1; tally = tmp;.

, , (. ., ). , tally =tally + 1; ( ).

5

1. increase() 9. x, 2 < x 10, tally x.

2. increase() 9. x, 1 < x 10, tally x; .

3. increase() :void increase()int tmp, i; /* */ begin

for i=0 to 50 dotally = tally + 1;

end

tally, ; tally;

4. increase() 9 3 2 . tally ;


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: tally 2. To 16. , (

tally ).5. tally

3;

6. 4 5 4 , 5 n .

: , tally 2.

3.2

. . , . , . , -11 .

. , Word Excel. (.doc, .xls) . - . ;

.

, . . . , :

. , / 2 1,80 , 3,60 1,5 2,75 3 4,12 4 0,25

1 . 1 0,5 0,5 , .

, , . , .

( ) ( ). , / , , ,


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70

. , . , . ( ) , , . , 17. front , back .

17: .

. back

. back 10. , back 10 ( 11). , 10 back 11. , 10. , . , front back.

. 500 , (. ., ).

, . , , .

:

file1.txtfile2.txt

89

10

front

back

.

.

.

.

.

.


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3 &

71

shared int balance;

boolean withdraw(int amount)begin

if (amount > balance)begin

print !;return FALSE;

endelse

beginbalance = balance amount;print ;print balance;return TRUE;

endend

, :

1. amount.

2. balance.

3. amount > balance " " .

4. , amount balance balance.

5. amount .

6. " " .

( ATM-1 ATM-2) 500 . ;

. , 500 . , . ( ). . 18.

1000 500 !


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3 &

72

( balance).

- . . .

ATM-1 ( ) ATM-2 ( )

amount = 500

balance = 500

if ( TRUE)

balance = balance amount

print print balance

amount = 500

balance = 500

if ( TRUE)

balance = balance amount

print print balance

18: 1000 500.

6

500

, (. ., ).

1500 , 500 , 1000 . 500.

, . , .

:

shared int balance;

boolean deposit(int amount)begin

balance = balance + amount;print ;print balance;return TRUE;

end


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73

. , 500 , 1000 ( 1500 ). !

3.3

(. ., ) . (race conditions ).

(. ., ) ( ). - . , . , . , . .

, ( ), , ( , ). , , :

;;;;

:

1. . ( ).

2. . ( ) , -


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74

, ( , ).

. , , - (. ., , ). - . ,

, . . .

( ) . , , , .. .

:

1. . .

2. . , .

- ( ). , 19 ( , 1 ).

1

2

3

repeat

begin;;;;

endforever;

repeatbegin

;;;;

enduntil FALSE;

while (TRUE)

begin;;;;

end

19: .


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75

, . . , , . , . 20 .

;

; /* */

;

;

; /*

*/ ...

; ;

;

;

;

.

.

.

20: .

20 .

3.4 , , . , , ( , ).

Test&Set() 21.


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3 &

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boolean Test&Set(boolean lock)

int tmp; /* */

begintmp = lock;lock = TRUE;return(tmp);

end

21: Test&Set().

H Test&Set() boolean lock. Test&Set() TRUE lock lock. , lock FALSE Test&Set(), Test&Set() FALSE, TRUE. , lock Test&Set() TRUE. Test&Set() lock. .

, Test&Set() ( Test&Set() Test&Set()).

22.

shared boolean lock; /* , , FALSE */

int tmp; /* */ repeatbegin

tmp = Test&Set(lock);while (tmp == TRUE) do tmp = Test&Set(lock);;lock = FALSE;;

endforever;

22: Test&Set().

lock FALSE, Test&Set() . , , Test&Set() FALSE, lock TRUE. FALSE tmp while FALSE. . Test&Set() TRUE ( , , lock TRUE). , while . ,


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77

lock FALSE .

7 ( 1, 5, 4, . 2001-2002 )

22 Test&Set() ;

Test&Set() . ( 0 1), . , 23 ( ).

0 1repeat

begintmp0 = lock;lock = TRUE;while (tmp0 == TRUE) do

tmp0 = Test&Set(lock);

;

lock = FALSE;

;

endforever;

repeatbegin

tmp1 = lock;lock = TRUE;while (tmp1 == TRUE) do

tmp1 = Test&Set(lock);

;

lock = FALSE;

;

endforever;

23: 0 1 Test&Set() .

23, tmp , tmp . , tmp. 24.

0 1tmp0 = lock;

lock = 1; while /* FALSE */ ;

tmp1 = lock;lock = 1; while /* FALSE */ ;


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78

24: Test&Set() .

0 lock ( FALSE) tmp0. 0 1. Test&Set() , 1 Test&Set() ( Test&Set() ). FALSE tmp1, lock FALSE . , 1 0. 0 lock TRUE, while FALSE ( tmp0 FALSE) .

8 ( 2, 4, . 2001-2002 ) ! , 3.2;

:

boolean deposit(int amount),

boolean withdraw(int amount),

:

deposit() amount , withdraw() amount .

, (. ., ), . .

Test&Set() .

- deposit() withdraw() 3.2. deposit() withdraw(), .

deposit() balance. deposit() 25.

shared int balance;

boolean deposit(int amount)


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79

int tmp; /* */ begin

tmp = Test&Set(lock);

while (tmp == TRUE) do tmp = Test&Set(lock);balance = balance + amount;print ;print balance;lock = FALSE;return TRUE;

end

25: deposit().

withdraw(). ( ) balance

. withdraw() 26.shared int balance;

boolean withdraw(int amount)begin

tmp = Test&Set(lock);while (tmp == TRUE) do tmp = Test&Set(lock);

if (amount > balance)begin

print !;lock = FALSE;return FALSE;

endelse

beginbalance = balance amount;print ;print balance;lock = FALSE;return TRUE;

endend

26: withdraw().

3.2 ( ) deposit() withdraw() 25 26.

9

15 ;


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80

.

, . . 27.

0 1

tmp = Test&Set(lock); while /* FALSE */

;lock = FALSE;;tmp = Test&Set(lock); while /* FALSE */

;lock = FALSE;;tmp = Test&Set(lock); while /* FALSE */

.

.

.

tmp = Test&Set(lock); while /* TRUE */

while /* TRUE */ while /* TRUE */ while /* TRUE */

while /* TRUE */ while /* TRUE */ ...

27: 1 Test&Set().

27 0. Test&Set() . 1 . 1 while . 0 , lock FALSE. 1, 0 - , Test&Set() lock TRUE. H 1 , . . 0 , 1 . 15 .


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81

, . , , . .

10 ( 3.19 )

Fetch&Add(), 28 . Fetch&Add(). ( Fetch&AddA() Test&Set() .)

int Fetch&Add(int a, int b)

int tmp; /* */

begintmp = a;a = a + b;return(tmp);

end

28: Fetch&Add().

;

: lock Fetch&Add() (. ., 1) Fetch&Add(), .

11

Swap(), 29 . Swap().

int Swap(int a, int b)

int tmp; /* */

begintmp = a;a = b;b = tmp;return(tmp);

end

29: Swap().

;


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82

: lock Swap() Swap(), .

12

RMW() (Read-Modify-Write()), 30 . RMW().

int RMW(int a, function f)

int tmp; /* */

begintmp = a;a = f(a);

return(tmp);end

30: RMW().

RMW() , a f(). a f ( f a a), a.

;

: f().

13 ( 2, 4, . 2001-2002 ) :

boolean deposit(int amount),

boolean withdraw(int amount),

8. :

1. Fetch&Add() ,

2. Swap() .

3. RMW() .

3.5

, ( . ., Test&Set()).


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83

3.5.1 ,

, . , , , , .

. 31, .

shared boolean in; /* , FALSE */

0 1

repeatbegin

while (in == TRUE) do noop;in = TRUE;;in = FALSE;;

endforever;

repeatbegin

while (in == TRUE) do noop;in = TRUE;;in = FALSE;;

endforever;

31: .

in, . in FALSE, TRUE . in TRUE, while. , in FALSE, noop ( while).

; ; , .

, 0 while in FALSE. 1 in TRUE . , 1. 1 while, in FALSE, 0 in TRUE


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84

. . in TRUE . 32.

while; /* FALSE */

free = TRUE; ;

while; /* FALSE */

free = TRUE;;

32: 1 .

, 31 .

. in FALSE in TRUE. , ( while) ( in TRUE). , . 33.

shared boolean flag[2]; /* , FALSE */

0 1

repeatbegin

flag[0] = TRUE;while (flag[1] == TRUE) do noop;

;flag[0] = FALSE;;

endforever;

repeatbegin

flag[1] = TRUE;while (flag[0] == TRUE) do noop;

;flag[1] = FALSE;;

endforever;

33: .

33, , . flag[i] i . , i flag[i] TRUE .


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85

( , 1-i) . , i . 1-i flag FALSE.

; noop while; .

0 1

flag[0] = RUE;

while; /* TRUE */

while; /* TRUE */ while; /* TRUE */ while; /* TRUE */ ...

/* while FALSE 0 while */

flag[1] = TRUE;

while; /* TRUE */

while; /* TRUE */ while; /* TRUE */ ...

/* while FALSE 1 while */

34: 2 .

34, while . 0 1 flag[1] FALSE, 1 0 flag[0] FALSE. . ,

( ), .

35.

shared int turn; /* , 0 1, */

0 1

repeatbegin

while (turn == 1) do noop;

repeatbegin

while (turn == 0) do noop;


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86

;turn = 1;;

endforever;

;turn = 0;;

endforever;

35: ( ) .

. . , turn 0 1 , while . . ., 1 . 1 , turn 1. , 0 , while . 1 , turn 0 0 . 1 , 0 turn 1. H 35 .

. , , - .

. 36 ( turn 1).

0 1

while; /* FALSE */ ;turn = 1;;

while; /* TRUE */ while; /* TRUE */

while; /* TRUE */ while; /* TRUE */ while; /* TRUE */

while; /* TRUE */ ...

while; /* FALSE */ ;turn = 0; - ;

- ;

- ;

.

.

.


87/143


88/143


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89

5. .

6.

.7. , .

8. .

:

1. .

2. .

3. , .

4. .

;

17

( ;). . . . , - . , .

:

5. , .

6. .

7. , , ( ).

:

1. , .

2. .

3. , , ( ).

; ( ) ;


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90

3.5.2 Peterson ,

. Peterson.

shared in turn; /* 0 1 */ shared boolean flag[2]; /* FALSE */

0 1

repeatbegin

1. flag[0] = TRUE;2. turn = 0;3. while (turn == 0 AND flag[1] == TRUE) do

noop;4. < >;5. flag[0] = FALSE; 6. < - >;

endforever;

repeatbegin

1. flag[1] = TRUE; 2. turn = 1;3. while (turn == 1 AND flag[0] == TRUE) do

noop;4. < >; 5. flag[1] = FALSE; 6. < - >;

endforever;

38: Peterson.

Peterson turn , flag , . i, , flag[i] TRUE turn i. . . , flag FALSE.

Peterso

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