18 Questions
What is the primary difference between non-preemptive and preemptive scheduling?
Non-preemptive scheduling does not allow the CPU to be taken away from its currently executing process.
What is the goal of maximizing CPU utilization?
To keep the CPU busy doing useful work at all times.
What is the First-Come, First-Served Algorithm (FCFS)?
A non-preemptive scheduling algorithm that executes processes in the order they arrive.
What is the primary goal of minimizing response time?
To minimize the time between the submission of a request and the start of the system’s first response.
What is the primary goal of maximizing throughput?
To maximize the amount of work done by the CPU.
What is the primary goal of minimizing turnaround time?
To minimize the time between the point a process is submitted and the time it finishes executing.
What is the main characteristic of the Shortest Process First Algorithm?
It executes the process with the shortest CPU burst time first
What happens in the Shortest Remaining Time First Algorithm when a process with a shorter CPU burst time arrives in the ready queue?
The currently executing process is preempted
What is the main difference between the Round Robin Algorithm and the First-Come-First-Served Algorithm?
The Round Robin Algorithm assigns a time limit to each process
What is the main goal of the Priority Scheduling algorithm?
To execute the process with the highest priority first
What is the main characteristic of the Multilevel Feedback Queues algorithm?
It permanently assigns processes to a queue on entry to the system
What problem might occur when two or more processes or threads are updated simultaneously?
Problems might occur
What is the primary issue with software solutions to the critical section problem?
Busy waiting
Which hardware solution enables a process to modify a variable or memory location atomically?
Special hardware instruction
What is the purpose of a semaphore in process synchronization?
To solve complex synchronization problems
What does the Dining Philosophers Problem represent?
Use of limited resources
What is a deadlock situation in process management?
Two or more processes waiting for resources held by each other
What is the primary difference between readers and writers in the Readers and Writers Problem?
Readers can only read data, while writers can modify or update data
Study Notes
CPU Scheduling
- Non-Preemptive scheduling: CPU cannot be taken away from currently executing process
- Preemptive scheduling: CPU can be taken away from currently executing process due to interrupt, higher priority process, or time limit exceeded
Performance Criteria for Schedulers
- CPU utilization: maximize CPU busy time
- Throughput: maximize work done by CPU
- Turnaround time: minimize time between process submission and completion
- Response time: minimize time between request submission and first response
- Waiting time: minimize time spent in ready queue
- Fairness: equal opportunity for all processes to use CPU
CPU Scheduling Algorithms
- First-Come, First-Served Algorithm (FCFS): non-preemptive, execute processes in order of arrival
- Shortest Process First Algorithm (SPF)/Shortest Job First Algorithm (SJF): non-preemptive, execute shortest CPU burst time first
- Shortest Remaining Time First Algorithm (SRTF): preemptive, execute shortest remaining CPU burst time first
- Round Robin Algorithm (RR): preemptive, execute in order of arrival with time limit (time quantum or time slice)
- Priority Scheduling: execute highest priority process, may be non-preemptive or preemptive
- Multilevel Feedback Queues: determine behavior pattern, permanently assign processes to queues
Process Synchronization
- Bakery Algorithm: assigns smallest number to processes, allowing entry to critical section
- Busy waiting: main problem with software solutions, stuck in while loop
Hardware Solutions to Critical Section Problem
- Disabling interrupts: disable interrupts before modifying shared variables
- Special hardware instruction: modify variables or memory locations atomically
Semaphore
- Special integer variable protected by atomic operations
- Solves complex synchronization problems without busy waiting
Classic Synchronization Problems
- Dining Philosophers Problem: represents processes using limited resources
- Deadlock: situation where two or more processes wait for resources held by each other
- Readers and Writers Problem: represents access to database, readers examine data, writers modify data
Understand the Bakery Algorithm and hardware solutions to the critical section problem, including disabling interrupts and special hardware instructions. Learn how to overcome busy waiting and synchronize access to shared variables.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
