49 lines
1.4 KiB
Python
49 lines
1.4 KiB
Python
import sys
|
|
|
|
def sjf_preemptive(processes, n):
|
|
remaining_time = [bt for _, _, bt in processes]
|
|
complete = 0
|
|
t = 0
|
|
minm = sys.maxsize
|
|
shortest = 0
|
|
finish_time = 0
|
|
check = False
|
|
waiting_time = [0] * n
|
|
turnaround_time = [0] * n
|
|
|
|
while complete != n:
|
|
for j in range(n):
|
|
if processes[j][1] <= t and remaining_time[j] < minm and remaining_time[j] > 0:
|
|
minm = remaining_time[j]
|
|
shortest = j
|
|
check = True
|
|
|
|
if not check:
|
|
t += 1
|
|
continue
|
|
|
|
remaining_time[shortest] -= 1
|
|
minm = remaining_time[shortest] if remaining_time[shortest] > 0 else sys.maxsize
|
|
|
|
if remaining_time[shortest] == 0:
|
|
complete += 1
|
|
check = False
|
|
finish_time = t + 1
|
|
waiting_time[shortest] = finish_time - processes[shortest][2] - processes[shortest][1]
|
|
|
|
if waiting_time[shortest] < 0:
|
|
waiting_time[shortest] = 0
|
|
|
|
t += 1
|
|
|
|
for i in range(n):
|
|
turnaround_time[i] = processes[i][2] + waiting_time[i]
|
|
|
|
print("\nSJF (Preemptive) Scheduling:")
|
|
for i, process in enumerate(processes):
|
|
print(f"Process {process[0]}: Waiting Time = {waiting_time[i]}, Turnaround Time = {turnaround_time[i]}")
|
|
|
|
# Input: Process ID, Arrival Time, Burst Time
|
|
processes = [[1, 0, 8], [2, 1, 4], [3, 2, 9], [4, 3, 5]]
|
|
sjf_preemptive(processes, len(processes))
|