Question

所以我正在编写一个时间片为1的简单Round Robin Scheduler。

这是输入（第一个数字是到达时间，第二个是突发时间）

这是预期的输出（cpu是正在执行的内容，就绪队列正在等待。字母表中的字母用于指示正在运行的进程以及剩余时间之后的数字）：< / p>

time   cpu   ready queue (pid/rst)
----   ---   ---------------------
  0    A3    --
  1    A2    --
  2    B6    A1
  3    A1    B5
  4    B5    C4
  5    C4    B4
  6    B4    D5, C3
  7    D5    C3, B3
  8    C3    B3, E2, D4
  9    B3    E2, D4, C2
 10    E2    D4, C2, B2
 11    D4    C2, B2, E1
 12    C2    B2, E1, D3
 13    B2    E1, D3, C1
 14    E1    D3, C1, B1
 15    D3    C1, B1
 16    C1    B1, D2
 17    B1    D2
 18    D2    --
 19    D1    --

但是我的就绪队列出错了。应该在抢占之前将到达物添加到就绪队列的后部（请参阅如何将D5添加到C3之前的就绪队列中）

这就是我得到的：

time    cpu ready_queue (pid/rst)
----    --- ---------------------
  0     A3  --
  1     A2  --
  2     B6  --
  3     A1  --
  4     B5  --
  5     C4  --
  6     D5  --
  7     B4  --
  8     C3  --
  9     D4  --
  10    E2  --
  11    B3  --
  12    C2  --
  13    D3  --
  14    E1  --
  15    B2  --
  16    C1  --
  17    D2  --
  18    B1  --
  19    D1  --

这是我的代码：

#include <stdio.h>
#include <stdlib.h>

#define TS 1

struct process
{
    char pid;
    int arrival_time;
    int service_time;
    int remaining_time;
    int departure_time;
    int turnaround_time;
    int wait_time;
};

struct process processes[26];
char pid_rst[2];
char alphabet[26] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
int num_processes = 0;
int total_time;

char* create_id(char c, int i)
{
    sprintf(pid_rst, "%c%d", c, i);

    return pid_rst;
}

void get_processes() 
{
    int a_t;
    int s_t;
    int i = 0;

    while((scanf("%d %d", &a_t, &s_t) == 2))
    {
        processes[i].pid = alphabet[i];
        processes[i].arrival_time = a_t;
        processes[i].service_time = s_t;
        processes[i].remaining_time = processes[i].service_time;

        i++;
        num_processes++;
        total_time += processes[i].service_time;
    }
}

int main()
{
    int time;
    int count;
    int remain;
    int flag = 0;
    int i;
    int w;

    get_processes();

    char* cpu_queue[1];
    char* wait_queue[num_processes];
    remain = num_processes;

    for(i = 0; i < num_processes; i++)
    {
        wait_queue[i] = "--";
    }

    printf("\ntime\tcpu\tready_queue (pid/rst)\n");
    printf("----\t---\t---------------------\n");

    for(time = 0, i = 0; remain != 0;) 
    {
        w = 1;
        if(processes[i].remaining_time <= TS && processes[i].remaining_time > 0)
        {
            printf("  %d\t%s\t%s\n", time, create_id(processes[i].pid, processes[i].remaining_time), wait_queue[w-1]);
            time += processes[i].remaining_time;
            processes[i].remaining_time = 0;
            flag = 1;   
        }
        else if (processes[i].remaining_time > 0)
        {
            printf("  %d\t%s\t%s\n", time, create_id(processes[i].pid, processes[i].remaining_time), wait_queue[w-1]);
            processes[i].remaining_time -= TS;
            time += TS;
        }
        if(processes[i].remaining_time == 0 && flag == 1)
        {
            remain--;
            processes[i].turnaround_time += time - processes[i].arrival_time;
            processes[i].wait_time += time - processes[i].arrival_time - processes[i].service_time;
            processes[i].departure_time = time;
            flag = 0;
        }
        if(i == num_processes-1)
        {
            i = 0;
        }
        else if(processes[i+1].arrival_time <= time)
        {
            wait_queue[w] = create_id(processes[i].pid, processes[i].remaining_time);
            if(w < 4)
                w++;
            i++;

        }
        else
        {
            i = 0;
        }
    }

    return 0;
}

循环调度问题

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