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1 "#! $ %! *+ &' & "-/ &+, :/!! &+ 8/!.!"!! > &, < &+ 7!! "-/ :/= +. :/= 0 0/ 7!@?+ C (" & + A &B' 7! G' 3/ 0"=' 7> H 0 4 0! &D E.! 0 n I"2 &+ % &B' 0!!! n 1 + counter J " &B' & K n </ 7! + &B' &+!!!808 + J :.%+ B 0! L 0M.+ N!! O8K + 8 N #define BUFFER_SIZE 10 typedef struct {... item; item buffer[buffer_size]; int in = 0; int out = 0; int counter = 0; :A &B' :(" 7!@ : C 7!@ item nextproduced; item nextconsumed; while (1) { while (counter == BUFFER_SIZE) ; /* do nothing */ buffer[in] = nextproduced; in = (in + 1) % BUFFER_SIZE; counter++; while (1) { while (counter == 0) ; /* do nothing */ nextconsumed = buffer[out]; out = (out + 1) % BUFFER_SIZE; counter--; 1

2 &T Q0"L &+ + counter 8 counter++ Q0R. " > Q0"L &+ + > Q/R U S@ &T.!S@ Q0"L &V8!K0 :+ Q0"L : &+, :/ Q0R : : 3+7 I!U counter++ register1 = counter register1 = register1 1 counter = register1 counter- - register2 = counter register2 = register2 1 counter = register2 Q0"L &+ X C 8 (" 7!@ 8! W 3+7 Q0"!, :/ H 780 &+ 0 % &B' 8/. " > (interleave) W+ 3 Q0"L &+ : N Q0"! 7. 8 counter = 5 Y IG +.(counter = 5 :"[ &T ) " > 0+. N 8 producer: register1 = counter (register1 = 5) producer: register1 = register1 + 1 (register1 = 6) consumer: register2 = counter (register2 = 5) consumer: register2 = register2 1 (register2 = 4) producer: counter = register1 (counter = 6) consumer: counter = register2 (counter = 4) &! '( Q0"L &+ 7!@ :] 3E 0! &, [ &M+) ^ J 0 E 8 0! +! A &B'!! &+ 8/.! + 3@ &/ 7 4@ & 7!@ Q/R &+!! 0M!! "-/.!0! %)+ 8/ 7!@ + &M+) ^ W"> +. " <%/ *+ )*! *+ )*! *+ )*!,) '( 7!@!U & E N@ [ 0! *+ &' &.,+V0!! &+ +! + "-+!! &+ +! &!0! *+ &'. 7!@.!0! 0V 3E 0! 0! 7!@. V8 &, & : :/= *+ &' & *+ &'!08 " / %! 7!@!0! 0V *+ &'.!"!"K,U / _ & + *+ &' & + ' 0.!7!08E+ 0!8* 0B 8,@ H& >8! & >8!,U / 7!@ ` H,!"K *+ &' > I' 0! 7!@ V8.!"!"K *+ &'!08 %!,@ 8,)!"K *+ &' > I' 0! 7!@ ` W - % E H) *+ &' &+!808 B 7!@!U!8* Q0"L &+ " / *+ &' &+!808 + U+ 7!@.!" &K 1"U &+.. 2

3 *+ )*!,) '(!8* 0B.! + H I0 0 *+ &' &+!808 =M 7!@ V8 7 V *+ &' &+ 7!@!808 QU! + 5+ '..+ &!!">8,"K0! 7!@ &+!808 7"T [R > L 7 W0+ R + 7!@ &/! Y 3".!S@ 3@ E *+ &' > 37 0! S( H " 7!@ >,R 3,) 0+0! a & "W ` 3" /.,! *,) ' P 2 8 P 1 7!@ 8! + ^M 0 3E + & ' +.! A J 7 %/ + " 7!@ :. : 7!@ 0K entry section exit section reminder section while (1); A J.L :!0M Hturn b*l!r.!"!"k *+ &'!08 " P i 7!@ turn == i :P i 7!@ while (turn!= i) ; turn = j; reminder section while (1);.K 0,@ H 0V+ 0 & >8!,U / _ A J.,0! :!0M Hflag 8! ("+ &0E.!"!"K *+ &'!08 " P i 7!@ flag [i] == true :P i 7!@ flag[i] := true; while (flag[j]) ; flag [i] = false; while (1);.K 0,@ H 0V+ 0 & >8!,U / _ 3 - (** -) * n,) flag [i]:= true; turn = j; while (flag [j] and turn = j) ; flag [i] = false; while (1); "%( 7 :P i 7!@ 0. 3"R &+ " :++ H 0V+ 0 _ &.!"! 7!@ 8! *+ &' & + '.,0!!R. *+ &' &+!808 7 N@ 7!@ *+ &'!08 + &! 0!R :]" & 7!@.!" P i % E i < j W H,0! 0!R. P j 8 P i 7!@ 8! W.!"!"K *+ &'!08 P j & W8 (" d + 0!R &/!R (" < Q0"L : &+ " 7T?. & "/ +. :+ 1, 2, 3, 3, 4, 4, 4, 5, 3

4 * n,) ** - &, &J(?. % + ]"!/ 0"%( : 0!.!" I/R (7!@ & H0!!R)? O87 80.a = c && b < d 8 i = 0,, n 1 + & /)V &+ k boolean choosing[n]; int number[n]; a < c (a, b) < (c, d),!r max (a 0,, a n-1 ).k a i + &! :A J. "!0M L 8,0!!M +? &+ & choosing[i] = true; number[i] = max(number[0], number[1],, number [n 1])+1; choosing[i] = false; for (j = 0; j < n; j++) { while (choosing[j]) ; while ((number[j]!= 0) && (number[j,j] < number[i,i])) ; number[i] = 0; while (1); *+ &' & & 0"! 7! + 3".! <%/ 0 7!@ " > S@ &T Q0"L &+ + S@ &T Q0"L &+ 0 &B' 7 &/. 0M :TestAndSet.!0M,0! &+ 0 3E 4# 8! &)M,0!. Y"R + S@ &T Q0"L &+ 0 J 8! 0M :Swap boolean TestAndSet(boolean &target) { boolean rv = target; tqrget = true; return rv; :TestAndSet :TestAndSet -3 7*8 19*.,0! 0M + lock ("+ J :A!! while (TestAndSet(lock)) ; lock = false; 7!@ :P i boolean lock; boolean waiting[n]; :Swap -3 7*8 19* :(,0! 0M +) A!! key = true; while (key == true) Swap(lock,key); lock = false; 7!@ :P i 4

5 63 *+ &' & 63 + ^M!0M 7 4@ &, b*l J.., +! +V signal 8 wait 0"! 8! 7! wait (S): while S 0 do no-op; S--; signal (S): S++; 63 4 *+ )*!,) 63 3 semaphore mutex; do { wait(mutex); signal(mutex); while (1); :(.!0M +) A!! 7!@ :P i typedef struct { int value; struct process *L; semaphore; :!" $U 7 Q0"L &+. 7 Q0"L &+ wakeup 8 block! Q/R 8! Y :+ $U.!08E 0! 1U,(' &+ 0 "K 7!@ > block.!w 7 0 P 1U 7!@ > wakeup (P) : $U Q0"L : & Q/R 5' wait(s): S.value--; if (S.value < 0) { add this process to S.L; block; %/ + "/R 0+ 3"R &+ 7 3".!! 7!@ 0! B Q/R 7 V /' P i 7!@ 0! A Q/R "K Y.!" > P j 7!@.! L 0M : + signal(s): S.value++; if (S.value <= 0) { remove a process P from S.L; wakeup(p); P i P j M M A wait(flag) signal(flag) B 5

6 +; 1! +; 1! Q0"L &+ ] 8! &!" &W [ &+ 1! 3/ 7 ^" + & )!K0 e"v8 B 3@ +.+ f 7!@ :+ L 0M + 8! Q 8 S Y & "/ + P 0 P 1 wait(s); wait(q); wait(q); wait(s); M M signal(s); signal(q); signal(q) signal(s); 7 7!@ - + LIFO < 7. Y,(' : 0!.! I% B 7!@ $L.+ N@ [*V, :/ 7!@ 0! 7!@ $L 7!,(' 0! :++.!" T [*V 8,)+ :+ &+ " & 63 & 63.0M 8! 8 0/ :!0!!">8 e" 8!,(' 0! 0!8*!M " &, b*l!r. 0/.! gk!"k &+.,. L 3E 0M &, b*l!r. 0M 8! 0M8! 7! + 0 0/. 3".! 7!@ :!! 0K binary-semaphore S1, S2; int C; :!0M S1 = 1; S2 = 0; C = initial value of S; wait operation wait(s1); C--; if (C < 0) { signal(s1); signal operation wait(s1); C ++; if (C <= 0) signal(s2); signal(s1); signal(s1); wait(s2); 43<,! *+ &' & 43<,! :7!@ %/. & & 0+ &+ N-+ : 0!!8* % &B' + C (" & )" 8 "K & C") 0"KSd & 6

7 semaphore full = 0, empty = n, mutex = 1; produce an item in nextp wait(empty); wait(mutex); add nextp to buffer signal(mutex); signal(full); while (1); :(!0M +) A!! :(" 7!@ wait(full) wait(mutex); remove an item from buffer to nextc signal(mutex); signal(empty); consume the item in nextc while (1); :(" 7!@!* *=!!* *=! semaphore mutex = 1, wrt = 1; int readcount = 0; wait(wrt); writing is performed signal(wrt); :(!0M +) A!! :)" 7!@ wait (mutex); readcount ++; if (readcount == 1) wait (wrt); signal (mutex); reading is performed wait (mutex); readcount --; if (readcount == 0) signal (wrt); signal (mutex); : "K 7!@ "!>6 =?@! "!>6 =?@! semaphore chopstick [5] = {1; :(!0M +) A!! wait (chopstick[i]) wait (chopstick[(i+1) % 5]) eat signal (chopstick[i]); signal (chopstick[(i+1) % 5]); think while (1); :< i C") 7!@ 7

8 *+ & *+ &' & *+ AB 8 wait >?,R0 <R 8 7,0!!,)+ :+ 8!! &+ 3/! signal,0! > : wait - signal!! &+ 3/! : signal - wait,)+ :+ : wait - wait 5+ b[ )" & + 0K 7! :!@ ' 0., 7!@ %/ + 5+ b[ 0K. *+ &M[ *+ & *+ & :!" 3R 7 Q0"L &+ T e" 7 v A J. v: shared T. B ), S@ 3 7 Q0R 0! v J &+! :(, ("+ J region v when B do S v J &+ " / %! 7!@ H!" > Q0R : V8. +! > 7 H e>0 A J. &+ &.,U / % 3/ H > 0 *+ &M[ Q0R "K 7!@. V B ("+ Q0R 0M.!" > Q0R H+,0! B W 0! %! 7!@ & 7 B 7!@ H+,0! B W.!",0! ++ B 0M 8 v &+ _"+ *+ &M[ C H(" & :& "/. :A!! struct buffer { int pool [n]; int count, in, out; ( ) *+ & region x when B do S 3 :! 0V A &B' 0! 0 nextp (" 7!@ region buffer when( count < n) { pool[in] = nextp; in:= (in+1) % n; count ++; :!0! + A &B' 7 0 & "/ C 7!@ region buffer when (count > 0) { nextc = pool[out]; out = (out+1) % n; count --; :+ gk 0 7 J x J &+ semaphore mutex, first-delay, second-delay; int first-count, second-count; :/= 0 *+ &M[ &+ 0*! mutex J. &M[!08 " B Q0R 3!"+,0! 2K &+ 7!@. W 4# 8 B first-delay 80 + H!" *+ $L &+ H B J 0M 0+8! "+ & E 7 N@.!" M second-delay 0B 8

9 region x when B do S 3 wait (mutex); while (!B) { first_count ++; if (second_count > 0) signal (second_delay); signal (mutex); wait (first_delay); first_count --; second_count ++; if (first_count > 0) signal (first_delay); signal (second_delay); wait (second_delay); second_count --; S; if (first_count > 0) signal (first_delay); if (second_count > 0) signal (second_delay); signal (mutex); *+ &' & (Monitors) C C C I 5+ b[ 0K 7 %! (Monitor) 3+!., 7!@ %/ monitor monitor-name { shared variable declarations procedure body P 1 {... procedure body P 2 {... procedure body Pn {... { initialization code. + H /+ B 3+!. 0! "+ 7!@. & + :!" 3R 7 Q0"L &+ _ J condition x, y;.!"! signal 8 wait I/R + " _ J & 7, $V" "K 7!@ U x.wait /R. > 0 x.signal /R %! 7!@ W $V" 7!@. MV! x.signal /R.!0 h ` /R : H+ $V" 7!@ C 4 > D( E- C 9

10 "!>6 "!>6 :3+! $U monitor dp { enum {thinking, hungry, eating state[5]; condition self[5]; void pickup(int i) // following slides void putdown(int i) // following slides void test(int i) // following slides void init { for (int i = 0; i < 5; i++) state[i] = thinking;!0s%+ 80 I%] H0!+ 80 I%] void pickup (int i) { void putdown (int i) { state [i] = hungry; state [i] = thinking; test [i]; // test left and right neighbors if (state [i]!= eating) test ((i+4) % 5); self [i].wait; test ((i+1) % 5); void test(int i) { if ( (state[(i + 4) % 5]!= eating) && (state[i] == hungry) && (state[(i + 1) % 5]!= eating)) { state[i] = eating; self[i].signal; C 3 C 3 semaphore mutex = 1; semaphore next = 0; int next-count = 0; wait(mutex); body of F; if (next-count > 0) signal(next) signal(mutex); :(!0M +) J :!" :%> 7 &U[V + F I80.!" :/= 3+! 0! 0*! :! gk 0/. 8. x _ J &+ semaphore x_sem = 0; int x_count = 0; : " 7!@ 7 Q0"L &+ x.signal 8 x.wait I/R x.wait x_count ++; if (next_count > 0) signal (next); signal (mutex); wait (x_sem); x_count --; x.signal if (x_count > 0) { next_count ++; signal (x_sem); wait (next); next_count --; C 3 C 3 0"%( 7 " +7+ 7!@ - + R ).! " 8 (FCFS) 7!@ : /V I8 ::!,"(8 <" 8 2 0B 0K 7! :%! X80.!" "K x.wait (c) Q0"L &+ 2 0B 0K.!" &* wait "K + &, b*l Q0R. c $V" 7!@ < / &+ 7!@,"(8 0/ 3"R &+ c 0M.!" Kj 0,"(8 0/ :]" & 7!@!" > x.signal V8.!" +7+ H+ &! monitor ResourceAllocation { boolean busy; condition x; void acquire (int time) { if (busy) x.wait (time); busy = true; void release { busy = false; x.signal ; void init { busy = false; // A Correct Use: R.acquire (t); access the resource R.release ; 10

11 F13 ( "B,GH I -!3 G> 1+J '( 08E!,)+ :+ 8 3/! 7,0!! 5+ b[ )" & + 0K 7! :!@ ' 0!!!, C2+ Q0"L &+ 7+ k &+ 7>?) 38+, :/ 7!@..!7E %D 0 & gk k, :/ 7!@...., :/ 7!@. )!/R,*L ^ I : ' 0 ( 18 ) l' < :+ ' 0 :!"7E 0 7 _ 8! + ),*L 7 3/2 +? ! 0!!"K "K !@.! <T b*l 0! k "+ 3+!!808 W0! 7 0"R 38+ 7!@ `.! gk!"k &+ 0 3+! 0K 2 KL *+ &' & 2 KL3 + V 7 - e" 2 405" 0!. 7!@ W7!@] 8 %0] mutex 7 " &U[V 0! 0 3!+5+,> 2 405".!!! 7,B* + M8 7 + &U[V 0!!! 7,B* +.!"! )" H "K V 8 _ J. 7 $V" 7!@ 3!? " 0!.!"! turnstile < &+,"(8 + $L 0K 2000 k+ 7,B* + 7!@. ) 0! ! (interrupt mask) &V8 M 7! spinlock V 7 7!@ ] ) 0! &U[V 7,B* + &) ^" V :.!". "! " 8 mutex 3"R &+ dispatcher object 7 3" :D/.!!,/'!K0 7 3" dispatcher object 7! +.!0! _ J &+ 0)+,!K0..!.! n@ 3@ Q5" : &+ 14 H10 H9 H8 H7 H6 H3 H2 :)" & + :/ 0+0! 4"( :3+ R ) C++ :7 & ! <T * N 0! 0 :/ : " :/ n@ 8-0! G' 0 * :/ n@. I0! 0! & ! G' 0 )" & + K < / 7 / 3!!,! 7 = n@ I0 0! 780 & 7 / K / / 3!!,! 7 = n@ I0 0! 780 & 7 N+ K 11