Question

我已经获得了一个从txt文件中读取模拟进程的赋值。

ID: 35; Arrival_Time: 0; Total_Exec_Time: 4;
ID: 65; Arrival_Time: 2; Total_Exec_Time: 6;
ID: 10; Arrival_Time: 3; Total_Exec_Time: 3;
ID: 124; Arrival_Time: 5; Total_Exec_Time: 5;
ID: 182; Arrival_Time: 6; Total_Exec_Time: 2;

我必须从（先到先得，最短剩余时间，最短剩余时间，循环q = 2）的选择中完成两个算法。我需要根据我选择的两个算法打印出当时运行的当前时间和进程。我已经成功完成了FCFS。我的下一个方法是关于SRT，除了我对算法背后的逻辑有一些严重的问题。

我目前正在尝试一种迭代方法（在下面发布），它在某种程度上起作用（直到当前时间9），但我觉得这可能只是一个幸运的巧合。

有没有人对此算法或其他两种算法之一有任何建议。我已经在这项任务上工作了好几天了，决定把我的骄傲吸收到堆叠上。

注意：这是我第一次使用shell脚本，所以我的代码可能有点乱。我仍在努力了解KornShell（ksh）。

file="/path/to/file.txt"
  IFS=': \;'
  i=0
  while read -r f1 f2 f3 f4 f5 f6  
    do 
      integer id[i]="$f2" #id array
      integer at[i]="$f4" #arrival time array
      integer et[i]="$f6" #exec time array
      integer rt[i]=0 #run time so far
      integer current[i]=i

      ((i++))
    done <"$file"

  integer curr_index=0
  integer currTime=0
  let totalProcesses=${#at[@]}
  let totalProcesses=totalProcesses-1
  let totalRunTime=0
  for x in ${et[@]}; do
    let totalRunTime+=$x
  done 

  scheduleTask () { 
    currTime=$1
    for y in ${current[@]}; do
      if (( rt[$y] < et[$y] )); then
        #if the program is not finished, keep going
        if (( at[$y] < $currTime )); then
          #if the program is in que, keep going
          let diff=et[$y]-rt[$y]#not currently using
          let currDiff=et[$curr_index]-rt[$curr_index] #not currently using         
          if (( et[$y] <= et[$curr_index] )); then #is this broken?
            curr_index=$y
          fi
        fi
      else
        echo "${id[$y]} RAN ${rt[$y]} out of ${et[$y]} seconds"

        unset current[$y]
      fi
    done
  }

  for (( i = 0; i < $totalRunTime; i++ )); do
    echo "================================="
    scheduleTask $i 
    ((rt[$curr_index]++))
    print "\t\tcurrent time: $i"
    print "\t\t\tcurrent process: ${id[$curr_index]}"
    echo "================================="
  done

SRT的正确输出应该是这样的..

=================================
        current time: 0
            current process: 35
=================================
=================================
        current time: 1
            current process: 35
=================================
=================================
        current time: 2
            current process: 35
=================================
=================================
        current time: 3
            current process: 35
=================================
=================================
        current time: 4
            current process: 10
=================================
=================================
        current time: 5
            current process: 10
=================================
=================================
        current time: 6
            current process: 10
=================================
=================================
        current time: 7
            current process: 182
=================================
=================================
        current time: 8
            current process: 182
=================================
=================================
        current time: 9
            current process: 124
=================================
=================================
        current time: 10
            current process: 124
=================================
=================================
        current time: 11
            current process: 124
=================================
=================================
        current time: 12
            current process: 124
=================================
=================================
        current time: 13
            current process: 124
=================================
=================================
        current time: 14
            current process: 65
=================================
=================================
        current time: 15
            current process: 65
=================================
=================================
        current time: 16
            current process: 65
=================================
=================================
        current time: 17
            current process: 65
=================================
=================================
        current time: 18
            current process: 65
=================================
=================================
        current time: 19
            current process: 65
=================================

Answer 1

我仍然相对较新的堆栈溢出，并且对于家庭作业的想法和意见天真。我正在讨论删除这个问题，但在阅读这篇文章后（https://meta.stackexchange.com/questions/10811/how-to-ask-and-answer-homework-questions），我认为我的问题符合指南，因此值得跟上。

我找出了最短剩余时间算法。我很感激没有人回答这个问题，我自己搞定算法（在TA的帮助下）是值得的。因此，我提供的答案将具有基本的伪逻辑，而没有实际的代码。

shortest = the first process read from the input(assuming it has already arrived)
while there are still processes to be run
     process = next process (out of processes that have not completed yet)
     if (process arrival time <= currentTime) #process arrived 
           if (process execution time < shortest execution time)
                 shortest = process

注意：这与我从TA（编写作业）收到的帮助大致相同，这就是为什么我觉得这个答案很舒服。

KornShell（ksh）调度算法（SRT）

1 个答案: