二 #include #include main() { int p1,p2; if(p1=fork()) /*子进程创建成功*/ putchar('b'); else { if(p2=fork()) /*子进程创建成功*/ putchar('c'); else putchar('a'); /*父进程执行*/ } } copy <运行结果> bca(有时会出现bac) 分析：从进程执行并发来看，输出bac,a #include #include main() { int p1,p2,i; if(p1=fork()) for(i=0;i<500;i++) printf("child %d\n",i); else { if(p2=fork()) for(i=0;i<500;i++) printf("son %d\n",i); else for(i=0;i<500;i++) printf("daughter %d\n",i); } } 〈运行结果〉 child…. son… daughter… daughter… 或child …son …child …son …daughter 分析：由于函数printf()输出的字符串之间不会被中断，因此，字符串内部的字符顺序输出时不变。但是 , 由于进程并发执行时的调度顺序和父子进程的抢占处理机问题，输出字符串的顺序和先后随着执行的不同而发生变化。这与打印单字符的结果相同。 #include #include main() { int p1,p2,i; if(p1=fork()) { lockf(1,1,0); for(i=0;i<500;i++) printf("child %d\n",i); lockf(1,0,0); } else { if(p2=fork()) { lockf(1,1,0); for(i=0;i<500;i++) printf("son %d\n",i); lockf(1,0,0); } else { lockf(1,1,0); for(i=0;i<500;i++) printf("daughter %d\n",i); lockf(1,0,0); } } } copy <运行结果〉大致与未上锁的输出结果相同，也是随着执行时间不同，输出结果的顺序有所不同。分析：因为上述程序执行时，不同进程之间不存在共享临界资源（其中打印机的互斥性已有由操作系统保证）问题，所以，加锁与不加锁效果相同。三 #include #include #include #include #include #include #define MSGKEY 75 /*定义关键词MEGKEY*/ struct msgform /*消息结构*/ { long mtype; char mtexe[1030]; /*文本长度*/ }msg; int msgqid,i; void CLIENT( ) { int i; msgqid=msgget(MSGKEY,0777); for(i=10;i>=1;i--) { msg.mtype=i; printf("(client)sent\n"); msgsnd(msgqid,&msg,1024,0); /*发送消息msg入msgid消息队列*/ } exit(0); } void SERVER( ) { msgqid=msgget(MSGKEY,0777|IPC_CREAT); /*由关键字获得消息队列*/ do { msgrcv(msgqid,&msg,1030,0,0); /*从队列msgid接受消息msg*/ printf("(server)receive\n"); }while(msg.mtype!=1); /*消息类型为1时，释放队列*/ msgctl(msgqid, IPC_RMID,0); exit(0); } int main() { if(fork()) SERVER(); else CLIENT( ); wait(0); wait(0); } copy <结果> 从理想的结果来说，应当是每当Client发送一个消息后，server接收该消息，Client再发送下一条。也就是说“(Client)sent”和“(server)received”的字样应该在屏幕上交替出现。实际的结果大多是，先由 Client 发送两条消息，然后Server接收一条消息。此后Client Server交替发送和接收消息.最后一次接收两条消息. Client 和Server 分别发送和接收了10条消息,与预期设想一致 #include #include #include #include #include #include #include #define SHMKEY 75 /*定义共享区关键词*/ int shmid,i; int *addr; int CLIENT() { int i; shmid=shmget(SHMKEY,1024,0777); /*获取共享区，长度1024，关键词SHMKEY*/ addr=shmat(shmid,0,0); /*共享区起始地址为addr*/ for(i=9;i>=0;i--) { while(*addr!= -1); printf("(client)sent\n"); /*打印（client）sent*/ *addr=i; /*把i赋给addr*/ } exit(0); } int SERVER() { shmid=shmget(SHMKEY,1024,0777|IPC_CREAT); /*创建共享区*/ addr=shmat(shmid,0,0); /*共享区起始地址为addr*/ do { *addr=-1; while(*addr==-1); printf("(server)received\n"); /*服务进程使用共享区*/ } while(*addr); shmctl(shmid,IPC_RMID,0); exit(0); } int main() { if(fork())SERVER(); if(fork())CLIENT(); wait(0); wait(0); } copy <结果〉运行的结果和预想的完全一样。但在运行的过程中，发现每当client发送一次数据后，server要等大约0.1秒才有响应。同样，之后client又需要等待大约0.1秒才发送下一个数据。 #include #include #include #include #include #include #include int pid1,pid2; main( ) { int fd[2]; char outpipe[100],inpipe[100]; pipe(fd); /*创建一个管道*/ while ((pid1=fork( ))==-1); if(pid1==0) { lockf(fd[1],1,0); sprintf(outpipe,"child 1 process is sending message!"); /*把串放入数组outpipe中*/ write(fd[1],outpipe,50); /*向管道写长为50字节的串*/ sleep(5); /*自我阻塞5秒*/ lockf(fd[1],0,0); exit(0); } else { while((pid2=fork( ))==-1); if(pid2==0) { lockf(fd[1],1,0); /*互斥*/ sprintf(outpipe,"child 2 process is sending message!"); write(fd[1],outpipe,50); sleep(5); lockf(fd[1],0,0); exit(0); } else { wait(0); /*同步*/ read(fd[0],inpipe,50); /*从管道中读长为50字节的串*/ printf("%s\n",inpipe); wait(0); read(fd[0],inpipe,50); printf("%s\n",inpipe); exit(0); } } } copy 〈运行结果〉延迟5秒后显示: child1 process is sending message! 再延迟5秒: child2 process is sending message! 四 #include #include #include #define TRUE 1 #define FALSE 0 #define INVALID -1 #define NUL 0 #define total_instruction 320 /*指令流长*/ #define total_vp 32 /*虚页长*/ #define clear_period 50 /*清零周期*/ typedef struct{ /*页面结构*/ int pn,pfn,counter,time; }pl_type; pl_type pl[total_vp]; /*页面结构数组*/ struct pfc_struct{ /*页面控制结构*/ int pn,pfn; struct pfc_struct *next; }; typedef struct pfc_struct pfc_type; pfc_type pfc[total_vp],*freepf_head,*busypf_head,*busypf_tail; int diseffect,a[total_instruction]; int page[total_instruction], offset[total_instruction]; void initialize(); void FIFO(); void LRU(); void OPT(); void LFU(); void NUR(); int main() { int S,i; srand((int)getpid()); S=(int)rand()%390; for(i=0;inext; pl[busypf_head->pn].pfn=INVALID; /*释放忙页面队列中的第一个页面*/ freepf_head=busypf_head; freepf_head->next=NUL; busypf_head=p; } p=freepf_head->next; /*按方式调新页面入内存页面*/ freepf_head->next=NUL; freepf_head->pn=page[i]; pl[page[i]].pfn=freepf_head->pfn; if(busypf_tail==NUL) busypf_head=busypf_tail=freepf_head; else { busypf_tail->next=freepf_head; busypf_tail=freepf_head; } freepf_head=p; } } printf("FIFO:%6.4F",1-(float)diseffect/320); } void LRU(total_pf) int total_pf; { int min,minj,i,j,present_time; initialize(total_pf);present_time=0; for(i=0;ipl[j].time&&pl[j].pfn!=INVALID) { min=pl[j].time; minj=j; } freepf_head=&pfc[pl[minj].pfn]; pl[minj].pfn=INVALID; pl[minj].time=-1; freepf_head->next=NUL; } pl[page[i]].pfn=freepf_head->pfn; pl[page[i]].time=present_time; freepf_head=freepf_head->next; } else pl[page[i]].time=present_time; present_time++; } printf("LRU:%6.4f",1-(float)diseffect/320); } void NUR(total_pf) int total_pf; { int i,j,dp,cont_flag,old_dp; pfc_type *t; initialize(total_pf); dp=0; for(i=0;inext=NUL; } pl[page[i]].pfn=freepf_head->pfn; freepf_head=freepf_head->next; } else pl[page[i]].counter=1; if(i%clear_period==0) for(j=0;jnext=NUL; pl[maxpage].pfn=INVALID; } pl[page[i]].pfn=freepf_head->pfn; freepf_head=freepf_head->next; } } printf("OPT:%6.4f",1-(float)diseffect/320); } void LFU(total_pf) /*LFU(leat Frequently Used) ALGORITHM*/ int total_pf; { int i,j,min,minpage; pfc_type *t; initialize(total_pf); for(i=0;ipl[j].counter&&pl[j].pfn!=INVALID) { min=pl[j].counter; minpage=j; } pl[j].counter=0; } freepf_head=&pfc[pl[minpage].pfn]; pl[minpage].pfn=INVALID; freepf_head->next=NUL; } pl[page[i]].pfn=freepf_head->pfn; freepf_head=freepf_head->next; } else pl[page[i]].counter++; } printf("LFU:%6.4f",1-(float)diseffect/320); } void initialize(total_pf) /*初始化相关数据结构*/ int total_pf; /*用户进程的内存页面数*/ { int i; diseffect=0; for(i=0;i 4 page framesFIFO:0.2594LRU:0.2562OPT:0.2687LFU:0.2437NUR:0.2625 5 page framesFIFO:0.3000LRU:0.3000OPT:0.3000LFU:0.2969NUR:0.2875 6 page framesFIFO:0.3375LRU:0.3281OPT:0.3281LFU:0.3094NUR:0.3281 7 page framesFIFO:0.3563LRU:0.3563OPT:0.3688LFU:0.3312NUR:0.3469 8 page framesFIFO:0.4031LRU:0.4094OPT:0.3875LFU:0.3406NUR:0.3781 9 page framesFIFO:0.4156LRU:0.4281OPT:0.4156LFU:0.3656NUR:0.4125 10 page framesFIFO:0.4281LRU:0.4469OPT:0.4313LFU:0.3750NUR:0.4406 11 page framesFIFO:0.4531LRU:0.4688OPT:0.4594LFU:0.4281NUR:0.4656 12 page framesFIFO:0.4656LRU:0.4813OPT:0.4906LFU:0.4375NUR:0.4938 13 page framesFIFO:0.4750LRU:0.5000OPT:0.5219LFU:0.4625NUR:0.5312 14 page framesFIFO:0.4906LRU:0.5125OPT:0.5375LFU:0.4938NUR:0.5500 15 page framesFIFO:0.5312LRU:0.5250OPT:0.5625LFU:0.5281NUR:0.5563 16 page framesFIFO:0.5406LRU:0.5625OPT:0.5813LFU:0.5531NUR:0.5844 17 page framesFIFO:0.5906LRU:0.5813OPT:0.6188LFU:0.5750NUR:0.6031 18 page framesFIFO:0.6000LRU:0.5906OPT:0.6344LFU:0.5906NUR:0.6250 19 page framesFIFO:0.6312LRU:0.6156OPT:0.6438LFU:0.6219NUR:0.6438 20 page framesFIFO:0.6406LRU:0.6344OPT:0.6625LFU:0.6438NUR:0.6750 21 page framesFIFO:0.6969LRU:0.6594OPT:0.6875LFU:0.6656NUR:0.6937 22 page framesFIFO:0.7000LRU:0.6781OPT:0.7125LFU:0.6813NUR:0.6844 23 page framesFIFO:0.7156LRU:0.6906OPT:0.7312LFU:0.7188NUR:0.6969 24 page framesFIFO:0.7438LRU:0.7219OPT:0.7531LFU:0.7438NUR:0.7469 25 page framesFIFO:0.7594LRU:0.7562OPT:0.7656LFU:0.7656NUR:0.7719 26 page framesFIFO:0.7750LRU:0.7812OPT:0.7937LFU:0.7781NUR:0.7781 27 page framesFIFO:0.8125LRU:0.7969OPT:0.8094LFU:0.8125NUR:0.7969 28 page framesFIFO:0.8344LRU:0.8313OPT:0.8281LFU:0.8313NUR:0.8406 29 page framesFIFO:0.8406LRU:0.8594OPT:0.8531LFU:0.8375NUR:0.8406 30 page framesFIFO:0.8625LRU:0.8781OPT:0.8750LFU:0.8562NUR:0.8594 31 page framesFIFO:0.8812LRU:0.8812OPT:0.8906LFU:0.8781NUR:0.8656 32 page framesFIFO:0.9000LRU:0.9000OPT:0.9000LFU:0.9000NUR:0.9000 五 /******************************************* makefile *******************************************/ filsys:main.o iallfre.o ballfre.o name.o access.o log.o close.o creat.o delete.o dir.o open.o rdwt.o format.o install.o halt.o cc-o filsys main.o iallfre.o ballfre.o name.o access.o log.o close.o creat.o delete.o dir.o open.o format.o install.o halt.o main.o:main.c filesys.h cc-c main.c igetput.o: igetput.c filesys.h cc-c igetput.c iallfre.o: iallfre.c filesys.h cc-c iallfre.c ballfre.o: ballfre.c filesys.h cc-c ballfre.c name.o:name.c filesys.h cc-c name.c access.o:access.c filesys.h cc-c access.c log.o:log.c filesys.h cc-c log.c close.o:close.c filesys.h cc-c close.c creat.c:creat.c filesys.h cc-c creat.c delete.o:delete.c filesys.h cc-c delete.c dir.o:dir.c filesys.h cc-c dir.c open.o:open.c filesys.h cc-c open.c rdwt.o:rdwt.c filesys.h cc-c rdwt.c format.o:format.c filesys.h cc-c format.c install.o: install.c filesys.h cc-c install.c halt.o:halt.c cc-c halt.c

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