class Kernel:
def __init__(self):
self.timer = Timer()
self.scheduler = Scheduler()
self.memory = RAM()
self.processes = []
self.cpus = [CPU(1)]
# print emulated specs
def bootUp(self):
print(f'Total CPU cores: {len(self.cpus)}')
print(f'Total RAM: {len(self.memory.memory)/2**20} MB')
print(f'Clock: {self.timer.clock} Hz')
print(f'Quantum: {self.timer.quantum} ms')
print(f'Page and frame size: {self.memory.mmu.pageSize/2**10} KB\n')
# read processes from processes.txt
def loadProcesses(self):
try:
with open('processes.txt', 'r') as f:
for line in f:
data = line.strip().split(',')
self.processes.append(Process(int(data[0]), int(data[1]), int(data[2]), int(data[3])))
except IOError:
print("File doesn't exist")
finally:
f.close()
# emulates scheduling and allocation of memory for a processes based on a scheduling algorithm
def schedulerRun(self):
stats = Stats()
while 1:
self.timer.setInitTime()
# checks for new processes to add to the ready queue and allocates memory on arrival
for process in self.processes:
if process.arrivalTime == self.timer.ticks:
self.scheduler.addProcess(process)
stats.output(self.timer, process, 'added')
for address in process.memAddresses:
self.memory.mmu.writeMemory(process, address, randint(0,256))
# sorts ready queue (non preemptive algorithms only)
self.scheduler.sortProcesses()
# simulate multiprocessing by using multiple cpus (if set)
for cpu in self.cpus:
try:
if cpu.currentProcess == None: # if cpu not running a process fetch the next available one
cpu.fetchProcess(self.scheduler.getAvailableProcess())
stats.output(self.timer, cpu.currentProcess, 'working', cpu.id)
else: cpu.runProcess() # else if already assigned a process increase its runtime
except IndexError: # if ready queue empty go to next cpu
continue
# handles finished process
if cpu.currentProcess.isFinished():
stats.turnaroundTimes.append(self.timer.ticks - cpu.currentProcess.arrivalTime)
stats.waitingTimes.append(stats.turnaroundTimes[-1] - cpu.currentProcess.burstTime)
stats.output(self.timer, cpu.currentProcess, 'finished')
# deallocate process' pages, remove process from cpu and readyqueue
for page in list(cpu.currentProcess.pageTable):
self.memory.mmu.deallocatePage(cpu.currentProcess, page)
self.scheduler.removeProcess(cpu.currentProcess)
cpu.freeCPU()
# fetch next process
try:
self.scheduler.sortProcesses()
cpu.fetchProcess(self.scheduler.getAvailableProcess())
stats.output(self.timer, cpu.currentProcess, 'working', cpu.id)
self.timer.resetQuantum()
except IndexError: # if ready queue is empty go to next cpu
continue
# handles a process time slice running out for preemptive algorithms
# frees the cpu and releases the process, reorders the ready queue and fetches the next available process
if (self.scheduler.strategy.name == 'RR' and self.timer.currentQuantum == self.timer.quantum):
cpu.freeCPU()
self.scheduler.strategy.sortProcesses()
cpu.fetchProcess(self.scheduler.getAvailableProcess())
stats.output(self.timer, cpu.currentProcess, 'working', cpu.id)
self.timer.resetQuantum()
# handles process accessing cpu for the first time
if (cpu.currentProcess.runTime == 0):
stats.responseTimes.append(self.timer.ticks - cpu.currentProcess.arrivalTime)
stats.output(self.timer, cpu.currentProcess, 'accessed')
# when all cpu are finished, go to next millisecond
self.timer.sleep()
self.timer.tick()
# when ready queue is empty end the simulation
if(len(self.scheduler.readyQueue) == 0):
break
results = stats.finalStats()
print('\n' + stats.finalStats() + '\n')
self.varReset()
return results
# reset variables every simulation
def varReset(self):
self.processes = []
self.timer.ticks=self.timer.currentQuantum = 0
self.memory.mmu.swap = {}
self.memory.mmu.history = []
# set number of cores to use for simulation
def setCpus(self, n):
self.cpus = []
for i in range(1, n+1):
self.cpus.append(CPU(i))
