Algoritma Shortest Remaining Time First (SRTF)

 

kode ini masih belum sempurna...masih ada beda sedikit dengan manual, 

tapi untuk memahami tidak masalah 

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# Python3 program to implement Shortest Remaining Time First 

# Shortest Remaining Time First (SRTF) 

# Function to find the waiting time 

# for all processes 

def findWaitingTime(processes, n, wt): 

rt = [0] * n 

# Copy the burst time into rt[] 

for i in range(n): 

rt[i] = processes[i][1] 

complete = 0

t = 0

minm = 999999999

short = 0

check = False

# Process until all processes gets 

# completed 

while (complete != n): 

# Find process with minimum remaining 

# time among the processes that 

# arrives till the current time` 

for j in range(n): 

if ((processes[j][2] <= t) and

(rt[j] < minm) and rt[j] > 0): 

minm = rt[j] 

short = j 

check = True

if (check == False): 

t += 1

continue

# Reduce remaining time by one 

rt[short] -= 1

# Update minimum 

minm = rt[short] 

if (minm == 0): 

minm = 999999999

# If a process gets completely 

# executed 

if (rt[short] == 0): 

# Increment complete 

complete += 1

check = False

# Find finish time of current 

# process 

fint = t + 1

# Calculate waiting time 

wt[short] = (fint - proc[short][1] -

proc[short][2]) 

if (wt[short] < 0): 

wt[short] = 0

# Increment time 

t += 1

# Function to calculate turn around time 

def findTurnAroundTime(processes, n, wt, tat): 

# Calculating turnaround time 

for i in range(n): 

tat[i] = processes[i][1] + wt[i] 

# Function to calculate average waiting 

# and turn-around times. 

def findavgTime(processes, n): 

wt = [0] * n 

tat = [0] * n 

# Function to find waiting time 

# of all processes 

findWaitingTime(processes, n, wt) 

# Function to find turn around time 

# for all processes 

findTurnAroundTime(processes, n, wt, tat) 

# Display processes along with all details 

print("Processes Burst Time Waiting", 

"Time Turn-Around Time") 

total_wt = 0

total_tat = 0

for i in range(n): 

total_wt = total_wt + wt[i] 

total_tat = total_tat + tat[i] 

print(" ", processes[i][0], "\t\t", 

processes[i][1], "\t\t", 

wt[i], "\t\t", tat[i]) 

print("\nAverage waiting time = %.5f "%(total_wt /n) ) 

print("Average turn around time = ", total_tat / n) 

# Driver code 

if __name__ =="__main__": 

# Process id's 

print ("algoritma Shortest Remaining Time First ")

print("             ")    

proc = [[1, 6, 1], [2, 8, 1], 

[3, 7, 2], [4, 4, 3]] 

n = 4

findavgTime(proc, n) 

# This code is contributed 

# Shubham Singh(SHUBHAMSINGH10) 

# modified by andrew  @2020

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