短作業(yè)優(yōu)先算法

1、短作業(yè)（進(jìn)程）優(yōu)先調(diào)度算法1. 短作業(yè)（進(jìn)程）優(yōu)先調(diào)度算法SJ（P）F，是指對(duì)短作業(yè)或短進(jìn)程優(yōu)先調(diào)度的算法。它們可以分別用于作業(yè)調(diào)度和進(jìn)程調(diào)度。短作業(yè)優(yōu)先（SJF）的調(diào)度算法是從后備隊(duì)列中選擇一個(gè)或若干個(gè)估計(jì)運(yùn)行時(shí)間最短的作業(yè)，將它們調(diào)入內(nèi)存運(yùn)行。而短進(jìn)程（SPF）調(diào)度算法則是從就緒隊(duì)列中選出一個(gè)估計(jì)運(yùn)行時(shí)間最短的進(jìn)程，將處理機(jī)分配給它，使它立即執(zhí)行并一直執(zhí)行到完成，或發(fā)生某事件而被阻塞放棄處理機(jī)再重新調(diào)度。SJ(P)F調(diào)度算法能有效地降低作業(yè)（進(jìn)程）的平均等待時(shí)間，提高系統(tǒng)吞吐量。該算法對(duì)長(zhǎng)作業(yè)不利，完全未考慮作業(yè)的緊迫程度。2. 流程圖開始獲取進(jìn)程信息按作業(yè)運(yùn)行時(shí)間排序調(diào)用action，執(zhí)

2、行進(jìn)程輸出結(jié)果結(jié)束3. 代碼#include<iostream.h>#include<string.h>#include<stdlib.h>struct sjfchar name10;float arrivetime;float servicetime;float starttime;float finishtime;float zztime;float dqzztime;sjf a100;void input(sjf *p,int N) int i;printf("intput the process's name & arriv

3、etime & servicetime:nfor exmple: a 0 100n");for(i=0;i<=N-1;i+)printf("input the %dth process's information:n",i+1);scanf("%s%f%f",&,&pi.arrivetime,&pi.servicetime);void Print(sjf *p,float arrivetime,float servicetime,float starttime,float finish

4、time,float zztime,float dqzztime,int N)int k; printf("run order:"); printf("%s",);for(k=1;k<N;k+)printf("->%s",); printf("nthe process's information:n"); printf("nnametarrivetservicetstarttfinishtzztdqzzn"); for(k=0;k<=N-1;

5、k+) printf("%st%-.2ft%-.2ft%-.2ft%-.2ft%-.2ft%-.2ftn",,pk.arrivetime,pk.servicetime,pk.starttime,pk.finishtime,pk.zztime,pk.dqzztime); /pai xuvoid sort(sjf *p,int N) for(int i=0;i<=N-1;i+) for(int j=0;j<=i;j+) if(pi.arrivetime<pj.arrivetime) sjf temp; temp=pi; pi=pj; pj=tem

6、p; /yun xing jieduanvoid deal(sjf *p, float arrivetime,float servicetime,float starttime,float finishtime,float &zztime,float &dqzztime,int N) int k; for(k=0;k<=N-1;k+) if(k=0) pk.starttime=pk.arrivetime; pk.finishtime=pk.arrivetime+pk.servicetime; else pk.starttime=pk-1.finishtime; pk.fi

7、nishtime=pk-1.finishtime+pk.servicetime; for(k=0;k<=N-1;k+) pk.zztime=pk.finishtime-pk.arrivetime; pk.dqzztime=pk.zztime/pk.servicetime; void sjff(sjf *p,int N)float arrivetime=0,servicetime=0,starttime=0,finishtime=0,zztime=0,dqzztime=0;sort(p,N); for(int m=0;m<N-1;m+) if(m=0) pm.finishtime=p

8、m.arrivetime+pm.servicetime; else pm.finishtime=pm-1.finishtime+pm.servicetime; int i=0; for(int n=m+1;n<=N-1;n+) if(pn.arrivetime<=pm.finishtime) i+; float min=pm+1.servicetime;int next=m+1;/m+1=n for(int k=m+1;k<m+i;k+) if(pk+1.servicetime<min) min=pk+1.servicetime; next=k+1; sjf temp;

9、 temp=pm+1; pm+1=pnext; pnext=temp; deal(p,arrivetime,servicetime,starttime,finishtime,zztime,dqzztime,N); Print(p,arrivetime,servicetime,starttime,finishtime,zztime,dqzztime,N);int main() int N; printf("-短作業(yè)優(yōu)先調(diào)度算法-n"); printf("input the process's number:n"); scanf("%d",&N); input(a,N); sjf *b=a; sjf *c=a; sjff(b,N); system("PAUSE");4. 運(yùn)行結(jié)果5. 心得體會(huì)課程設(shè)計(jì)結(jié)束了，在這次的課程設(shè)計(jì)中不僅檢驗(yàn)了我所學(xué)習(xí)的知識(shí)，也培養(yǎng)了我如