处理机的调度.doc

操作系统实验报告学号540907010126： 姓名：刘岩岩 班级：计科09-1 处理机的调度一、 实验目的（1） 通过编写程序实现进程或作业先来先服务、高优先权、按时间片 轮转调度算法，进一步掌握进程调度的概念和算法，加深对处理机分配的理解。（2） 了解 Linux 中进程（线程）的调度机制。（3） 学习使用 Linux 中进程（线程）调度算法，掌握相应的与调度有关的函数。二、 实验内容与步骤： 程序说明: 1） 先来先服务算法：如果早就绪的进程排在就绪队列的前面，迟就绪的进 程排在就绪队列的后面，那么先来先服务（FCFS：first come first service）总是把当前处于就绪队列之首的那个进程调度到运行状态。2） 2)轮转法就是按一定时间片(记为 q)轮番运行各个进程。如果 q 是一个定 值，则轮转法是一种对各进程机会均等的调度方法。3)优先级调度的基本思想是，把当前处于就绪队列中优先级最高的进程投 入运行，而不管各进程的下一个 CPU 周期的长短和其他因素。三、具体步骤: 分析问题，提出解决问题的算法 编制程序 程序调试 记录实验结果，以及思考是否能够改善算法 四、 程序及运行结果:#include #include #define P_NUM 5#define P_TIME 50 enum state ready,execute,block,finish ; struct pcbb char name4;int priority; /数越大优先级越高int cputime; /已占用CPU的时间int needtime; /执行时间int count; enum state process; struct pcbb *next; ; typedef struct pcbb pcb; void display_menu() printf(CHOOSE THE ALGORITHM:n); printf(1 PRIORITYn);printf(2 ROUNDROBINn); printf(3 EXITn); pcb* get_process()pcb *q; pcb *p; /头指针pcb *t; /尾指针int i = 0;printf(input name and timen); while (i name); scanf(%d,&q-needtime);q-cputime = 0; q-priority = P_TIME - q-needtime; q-process = ready; q-next = NULL; if(i=0)p = q;t = q; elset-next = q;t = q; i+; return p; void free_process(pcb *p)pcb *q; while(p!= NULL)q = p;p = p-next; free(q); void display(pcb *p)printf(name cputime needtime priority staten); while(p)printf(%s,p-name); printf( );printf(%d,p-cputime); printf( ); printf(%d,p-needtime); printf( ); printf(%d,p-priority); printf( );switch(p-process)case ready:printf(readyn);break; case execute:printf(executen); break;case block:printf(blockn); break; case finish:printf(finishn); break; p = p-next; int process_finish(pcb *q) int b1 = 1; while(b1&q)b1 = b1&q-needtime=0; q = q-next; return b1; void cpuexe(pcb *q)pcb *t = q; int tp = 0; while(q) /让t指向优先级最高的进程 if (q-process!=finish) q-process = ready; if(q-needtime=0) q-process = finish; if(tppriority&q-process!=finish)tp = q-priority;t = q; q = q-next; if(t-needtime!=0) t-priority -=3;/每执行一次优先级降低三个单位 t-needtime -; t-process = execute; t-cputime+; void priority_cal()pcb *p;p = get_process();int cpu = 0;while(!process_finish(p) /就绪队列中还有进程cpu+; printf(cputime:%dn,cpu);cpuexe(p); /选择优先级最高的进程执行一个时间单位 display(p); /每调度一次就显示次 free_process(p); /释放所有进程printf(All processes have finishedn); pcb *get_process_round() pcb *q;pcb *p; /头指针pcb *t; /尾指针int i = 0;printf(input name and timen); while (iname); scanf(%d,&q-needtime); q-cputime = 0; q-count = 0; q-process = ready; q-next = NULL; if(i=0)p = q;t = q; else t-next = q; t = q;i+; return p; void cpu_round(pcb *q) if(q-needtime=1) q-cputime+; else q-cputime +=2; q-needtime -=2;if(q-needtimeneedtime = 0; q-count+; q-process = execute; pcb *get_next(pcb *k,pcb *head)pcb *t; t = k; dot =t-next; while ( t & t-process = finish); if(t = NULL) t = head; /k是刚刚被执行的节点,如果t-next=k,所明就绪队列除了k和t以外都已结 束,按照时间片轮转算法,该t执行while(t-next!=k & t-process = finish)t = t-next; return t; void set_state(pcb *p) while(p) if(p-needtime = 0) p-process = finish; if(p-process = execute)p-process = ready; p = p-next; void display_round(pcb *p) printf(name cputime needtime count staten); while(p)printf(%s,p-name); printf( );printf(%d,p-cputime); printf( );printf(%d,p-needtime); printf( ); printf(%d,p-count); printf( );switch(p-process)case ready:printf(readyn);break; case execute:printf(executen);break;case block:printf(blockn); break; case finish:printf(finishn); break; p = p-next; void round_cal() pcb *p; pcb *r; p = get_process_round(); int cpu = 0; r=p; while(!process_finish(p) /就绪队列中还有进程if(r-needtime=1) cpu+=1; elsecpu+=2; /时间片长度是2cpu_round(r); r = get_next(r,p); /获得下一个需要执行的进程 printf(cputime:%dn,cpu);display_round(p); /每调度一次就显示次 set_state(p); free_process(p);/释放所有进程main()display_menu();int k; scanf(%d,&k); switch(k)case 1:priority_cal();break; case 2:round_cal();break;case 3: break; default