原算法中被選中任務每運行一個時間單位便將控制權交給主線程。再判斷是否需要切換實時任務。實際上不需這樣頻繁的時鐘中斷。

故改進成。只在需要重新調度任務時才返回主控線程。且統計出線程切換次數(主線程切換不計)。

//編譯

//?pthread庫不是Linux系統默認的庫，所以在編譯中需加-lpthread參數(posix線程庫 )

gcc -lpthread -lm test.c -o test.out

#include "math.h"

#include "sched.h"

#include "pthread.h"

#include "stdlib.h"

#include "semaphore.h"

//@author vince

typedef struct{

char task_id;

int call_num; //times has been called

int ci; //processing time

int ti; //T

int ci_left;

int ti_left; //time left to next T

int flag; //isActive,0_no,2_yes

int arg; //argument

pthread_t th; //thread

}task;

void proc(int *args);

void idle();

int select_proc();

int task_num=0;

int idle_num=0;

int alg; //1 for EDF, 2 for RMS

int curr_proc=-1; //index

int demo_time=100; //time for show

task *tasks;

pthread_mutex_t proc_wait[100]; //the one be chosed is unlocked

pthread_mutex_t main_wait,idle_wait;

float sum=0;

pthread_t idle_proc;

int i;

int switchCount=0;

int main(int argc,char **argv)

{

pthread_mutex_init(&main_wait,NULL);

pthread_mutex_lock(&main_wait); //

pthread_mutex_init(&idle_wait,NULL);

pthread_mutex_lock(&idle_wait); //

printf("Please input number of real time tasks : \n");

scanf("%d",&task_num);

tasks=(task*)malloc(task_num*sizeof(task));

for(i=0;ir)

{ //unschedulable

printf("(sum=%lf > r=%lf),not schedulable!\n",sum,r);

exit(2);

}

pthread_create(&idle_proc,NULL,(void*)idle,NULL);

//create idle proc

for(i=0;i0)

{

//pthread_mutex_lock(&proc_wait[*args]); //wait to be chosed

if(idle_num!=0)

{

printf("idle(%d)",idle_num);

idle_num=0;

}

printf("%c%d",tasks[*args].task_id,tasks[*args].call_num);

tasks[*args].ci_left--;

if(tasks[*args].ci_left==0)

{

printf("(%d)",tasks[*args].ci);

tasks[*args].flag=0;

tasks[*args].call_num++;

//pthread_mutex_unlock(&main_wait); //wake up main proc

//pthread_mutex_lock(&proc_wait[*args]);

}

int j;

//once it process,count rather than count in main(),coz it need to select in right here!

for(j=0;j");

idle_num++;

int j;

//once it process,count rather than count in main(),coz it need to select in right here!

for(j=0;jtasks[j].ti_left){

temp1=tasks[j].ti_left;

temp2=j;

break; }

case 2: //RMS

if(temp1>tasks[j].ti){

temp1=tasks[j].ti;

temp2=j; }

}

}

}

return temp2;

}

歡迎討論。

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