ENSF 461 Midterm Exam Questions and
Verified Answers |Already Graded A+|
2026 Brand New Version!!!
preemptive scheduling - Correct Answer -stops one process to run a different
process
STCF - Correct Answer -- the job that has the least amount of time remaining
should be scheduled, preempting any running jobs
- Pros: convoy-effect is no longer an issue
- Cons: we don't always know how long a job will take; not great for response time
T(response) - Correct Answer -T(first run) - T(arrival)
RR (Round Robin) - Correct Answer -each job be run for a fixed duration of time
(time slice) before switching
- Pros: good response time, fair since each job receives share of execution time
- Cons: more time is spent on context switching and less is spent on job execution
, MLFQ - Correct Answer -- places jobs into queues and each job is assigned a
priority level
- the job with the highest priority level queues first
- all jobs start at the highest priority, but can still move down
- scheduling jobs with the RR scheduler for example, we'll observe how much of a
time slice a job uses to estimate the job type (if it uses the whole time slice,
assume long running job)
- boosting priority ensures that a job is not starved for execution time
- Pros: good for mixed workloads without knowledge
- Cons: we don't know how to parameterize the system, how many queues, how
big time slices should be, how frequently to boost etc.
Proportional share scheduler - Correct Answer -gives every job a fair share of
resources
Lottery scheduling (probabilistic method of proportional share scheduling) -
Correct Answer -- scheduler assigns lottery tickets to jobs and the job is scheduled
when it wins the lottery
- the more tickets a job has, the more chances it has to win
- assigns CPU resources to the process that wins the lottery
Verified Answers |Already Graded A+|
2026 Brand New Version!!!
preemptive scheduling - Correct Answer -stops one process to run a different
process
STCF - Correct Answer -- the job that has the least amount of time remaining
should be scheduled, preempting any running jobs
- Pros: convoy-effect is no longer an issue
- Cons: we don't always know how long a job will take; not great for response time
T(response) - Correct Answer -T(first run) - T(arrival)
RR (Round Robin) - Correct Answer -each job be run for a fixed duration of time
(time slice) before switching
- Pros: good response time, fair since each job receives share of execution time
- Cons: more time is spent on context switching and less is spent on job execution
, MLFQ - Correct Answer -- places jobs into queues and each job is assigned a
priority level
- the job with the highest priority level queues first
- all jobs start at the highest priority, but can still move down
- scheduling jobs with the RR scheduler for example, we'll observe how much of a
time slice a job uses to estimate the job type (if it uses the whole time slice,
assume long running job)
- boosting priority ensures that a job is not starved for execution time
- Pros: good for mixed workloads without knowledge
- Cons: we don't know how to parameterize the system, how many queues, how
big time slices should be, how frequently to boost etc.
Proportional share scheduler - Correct Answer -gives every job a fair share of
resources
Lottery scheduling (probabilistic method of proportional share scheduling) -
Correct Answer -- scheduler assigns lottery tickets to jobs and the job is scheduled
when it wins the lottery
- the more tickets a job has, the more chances it has to win
- assigns CPU resources to the process that wins the lottery
