def sjf_preemption(plist):
"""
Shortest Job First (sjf). As processes arrive, execute them in
increasing order of burst time.
"""
TIME, completed, num_processes = -1, 0, len(plist)
ready_q = []
running_process, prev_process = None, None
TIMECS_REMAINING = 0
p_completed = CompletedPlist()
while completed < num_processes:
TIME += 1
# handle total wait time for each process
for p in ready_q:
p.time_q += 1
# populate ready_q
for p in plist:
if p.arrived == TIME:
heapq.heappush(ready_q, p)
p.arrives(TIME)
# execute the first process in the ready_q, if one exists
try:
if running_process is None:
running_process = heapq.heappop(ready_q)
if running_process.popped is None:
running_process.popped = TIME
# indicate a context switch. 10 ms to select and resume
# the new process
# fix this
pr.switches(prev_process, running_process, TIME)
TIMECS_REMAINING += 10
# if ready_q empty, can't execute any processes
except IndexError:
if TIMECS_REMAINING == 0:
prev_process = None
continue
# if a context switch is occurring, wait until it finishes
if TIMECS_REMAINING > 0:
TIMECS_REMAINING -= 1
continue
# If a preemption occurs, print a message indicating a context switch.
# Then, switch the current process with the one on top of the heap
if preempts(running_process, ready_q):
prev_process = running_process
pr.switches(running_process, ready_q[0], TIME)
heapq.heappush(ready_q, running_process)
running_process = heapq.heappop(ready_q)
if running_process.popped is None:
running_process.popped = TIME
if running_process.is_complete():
running_process.completes(TIME)
p_completed.push(running_process)
completed += 1
# we will not check for a context switch until the
# next iteration, decrement time. this way, a context switch will
# begin immediately as a process completes
TIME -= 1
# 7 ms in context switch to clear old process
prev_process = running_process
TIMECS_REMAINING += 7
running_process = None
else:
running_process.time -= 1
return p_completed
def sjf(plist):
"""
Shortest Job First (sjf). As processes arrive, execute them in
increasing order of burst time.
"""
TIME, completed, num_processes = -1, 0, len(plist)
ready_q = []
running_process, prev_process = None, None
TIMECS_REMAINING = 0
p_completed = CompletedPlist()
while (completed < num_processes):
TIME += 1
# handle total wait time for each process
for p in ready_q:
p.time_q += 1
# populate ready_q
for p in plist:
if (p.arrived == TIME):
heapq.heappush(ready_q, p)
p.arrives(TIME)
# execute the first process in the ready_q, if one exists
try:
if (running_process is None):
running_process = heapq.heappop(ready_q)
if (running_process.popped is None):
running_process.popped = TIME
# indicate a context switch. 10 ms to select and resume
# the new process
pr.switches(prev_process, running_process, TIME)
TIMECS_REMAINING += 10
# if ready_q empty, can't execute any processes
except IndexError:
if (TIMECS_REMAINING == 0):
prev_process = None
continue
# if a context switch is occurring, wait until it finishes
if (TIMECS_REMAINING > 0):
TIMECS_REMAINING -= 1
continue
if (running_process.is_complete()):
running_process.completes(TIME)
p_completed.push(running_process)
completed += 1
# we will not check for a context switch until the
# next iteration, decrement time. this way, a context switch will
# begin immediately as a process completes
TIME -= 1
# 7 ms in context switch to clear old process
prev_process = running_process
TIMECS_REMAINING += 7
running_process = None
else:
running_process.time -= 1
return p_completed
def roundrobin(plist):
"""
Shortest Job First (sjf). As processes arrive, execute them in
increasing order of burst time.
"""
TIME, completed, num_processes = -1, 0, len(plist)
ready_q = []
running_process, prev_process = None, None
TIMECS_REMAINING = 0
TIMERR_REMAINING = 0
p_completed = CompletedPlist()
while (completed < num_processes):
TIME += 1
TIMERR_REMAINING -= 1
# handle total wait time for each process
for p in ready_q:
p.time_q += 1
# populate ready_q
for p in plist:
if (p.arrived == TIME):
ready_q.append(p)
p.arrives(TIME)
# execute the first process in the ready_q, if one exists
try:
if (running_process is None):
TIMERR_REMAINING = TIME_SLICE
running_process = ready_q.pop(0)
if (running_process.popped is None):
running_process.popped = TIME
# indicate a context switch. 10 ms to select and resume
# the new process
pr.switches(prev_process, running_process, TIME)
TIMECS_REMAINING += 10
# if ready_q empty, can't execute any processes
except IndexError:
if (TIMECS_REMAINING == 0):
prev_process = None
continue
# if a context switch is occurring, wait until it finishes
if (TIMECS_REMAINING > 0):
TIMECS_REMAINING -= 1
continue
# if the time slice is complete, indicate a context switch, put
# the current process at the end of the ready_q, and grab another
# process out of the ready_q
if (TIMERR_REMAINING == 0):
ready_q.append(running_process)
pr.switches(running_process, ready_q[0], TIME)
prev_process = running_process
running_process = ready_q.pop(0)
if (running_process.popped is None):
running_process.popped = TIME
TIMERR_REMAINING = TIME_SLICE
TIMECS_REMAINING += TCS
if (running_process.is_complete()):
running_process.completes(TIME)
p_completed.push(running_process)
completed += 1
# we will not check for a context switch until the
# next iteration, decrement time. this way, a context switch will
# begin immediately as a process completes
TIME -= 1
# 7 ms in context switch to clear old process
prev_process = running_process
TIMECS_REMAINING += 7
running_process = None
else:
running_process.time -= 1
return p_completed
