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Questions and Answers
What is the short definition of a process?
What is the short definition of a process?
- A process is a 'set of global variables.'
- A process is a 'program code in a file.'
- A process is a 'program in execution.' (correct)
- A process is a 'collection of function parameters.'
What does the data section of a process contain?
What does the data section of a process contain?
- Temporary data
- Global variables (correct)
- Local variables
- Return addresses
What is the key concept underlying modern operating system design?
What is the key concept underlying modern operating system design?
- A process (correct)
- Heap memory management
- Multithreading
- Asynchronous activities
What type of activities does an operating system involve?
What type of activities does an operating system involve?
What is the address space of a process typically?
What is the address space of a process typically?
In Round Robin scheduling, if there are 4 processes in the ready queue and the time quantum is 10 milliseconds, what is the maximum time any process has to wait to get CPU time?
In Round Robin scheduling, if there are 4 processes in the ready queue and the time quantum is 10 milliseconds, what is the maximum time any process has to wait to get CPU time?
If the burst times for processes P1, P2, P3, and P4 in Round Robin scheduling with time quantum 20 are 25, 15, 30, and 20 respectively, what is the completion time of process P3?
If the burst times for processes P1, P2, P3, and P4 in Round Robin scheduling with time quantum 20 are 25, 15, 30, and 20 respectively, what is the completion time of process P3?
What is the purpose of Round Robin scheduling in interactive systems?
What is the purpose of Round Robin scheduling in interactive systems?
In Round Robin scheduling, if the time quantum is very large, what effect does this have on short CPU burst processes?
In Round Robin scheduling, if the time quantum is very large, what effect does this have on short CPU burst processes?
How does the turnaround time of long CPU burst processes change in Round Robin scheduling?
How does the turnaround time of long CPU burst processes change in Round Robin scheduling?
Which event does not cause process creation?
Which event does not cause process creation?
What is the purpose of the fork() system call in UNIX?
What is the purpose of the fork() system call in UNIX?
What are the possible process states in an operating system?
What are the possible process states in an operating system?
How are processes created and deleted in an operating system?
How are processes created and deleted in an operating system?
What does the process control block (PCB) contain information about?
What does the process control block (PCB) contain information about?
What are the benefits of using threads?
What are the benefits of using threads?
What are the states that threads go through?
What are the states that threads go through?
What are the disadvantages of user-level threads?
What are the disadvantages of user-level threads?
What are the types of thread implementations mentioned in the text?
What are the types of thread implementations mentioned in the text?
What is the role of kernel threads?
What is the role of kernel threads?
What are some of the performance terms associated with scheduling?
What are some of the performance terms associated with scheduling?
What are the scheduling objectives mentioned in the text?
What are the scheduling objectives mentioned in the text?
What are some of the threading issues mentioned in the text?
What are some of the threading issues mentioned in the text?
What does low-level scheduling involve?
What does low-level scheduling involve?
What is a characteristic of program behavior mentioned in the text?
What is a characteristic of program behavior mentioned in the text?
What is the main performance metric for FCFS scheduling?
What is the main performance metric for FCFS scheduling?
What is the preemptive version of Shortest-Job-First (SJF) scheduling known as?
What is the preemptive version of Shortest-Job-First (SJF) scheduling known as?
What technique can be used to solve the problem of starvation in priority scheduling?
What technique can be used to solve the problem of starvation in priority scheduling?
In FCFS scheduling, what occurs when short processes wait behind long processes?
In FCFS scheduling, what occurs when short processes wait behind long processes?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What does the data section of a process contain?
What does the data section of a process contain?
What is the key concept underlying modern operating system design?
What is the key concept underlying modern operating system design?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What are some of the threading issues mentioned in the text?
What are some of the threading issues mentioned in the text?
What type of activities does an operating system involve?
What type of activities does an operating system involve?
In Round Robin (RR) scheduling, if there are 4 processes in the ready queue and the time quantum is 20 milliseconds, what is the maximum time any process has to wait to get CPU time?
In Round Robin (RR) scheduling, if there are 4 processes in the ready queue and the time quantum is 20 milliseconds, what is the maximum time any process has to wait to get CPU time?
What is the completion time of process P3 in Round Robin (RR) scheduling with time quantum 20, if the burst times for processes P1, P2, P3, and P4 are 25, 15, 30, and 20 respectively?
What is the completion time of process P3 in Round Robin (RR) scheduling with time quantum 20, if the burst times for processes P1, P2, P3, and P4 are 25, 15, 30, and 20 respectively?
What is the main goal of Round Robin (RR) scheduling?
What is the main goal of Round Robin (RR) scheduling?
What happens to the turnaround time of long CPU burst processes in Round Robin (RR) scheduling?
What happens to the turnaround time of long CPU burst processes in Round Robin (RR) scheduling?
What is the formula to calculate the maximum waiting time for any process in Round Robin (RR) scheduling?
What is the formula to calculate the maximum waiting time for any process in Round Robin (RR) scheduling?
What are the advantages of user-level threads?
What are the advantages of user-level threads?
What is a disadvantage of kernel threads compared to user-level threads?
What is a disadvantage of kernel threads compared to user-level threads?
What is a characteristic of thread operations?
What is a characteristic of thread operations?
What type of thread implementation reduces context switch times and eliminates kernel overhead?
What type of thread implementation reduces context switch times and eliminates kernel overhead?
How do multiple threaded processes enhance throughput and performance?
How do multiple threaded processes enhance throughput and performance?
What is the purpose of the fork() system call in UNIX?
What is the purpose of the fork() system call in UNIX?
What are the possible process states in an operating system?
What are the possible process states in an operating system?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What does the process control block (PCB) contain information about?
What does the process control block (PCB) contain information about?
What are some of the threading issues mentioned in the text?
What are some of the threading issues mentioned in the text?
What is the main performance metric for First Come First Serve (FCFS) scheduling?
What is the main performance metric for First Come First Serve (FCFS) scheduling?
What is the preemptive version of Shortest-Job-First (SJF) scheduling known as?
What is the preemptive version of Shortest-Job-First (SJF) scheduling known as?
What problem may occur in priority scheduling and can be solved using aging?
What problem may occur in priority scheduling and can be solved using aging?
What is the term for the effect in FCFS scheduling when short processes wait behind long processes?
What is the term for the effect in FCFS scheduling when short processes wait behind long processes?
What is the main goal of Shortest-Job-First (SJF) scheduling?
What is the main goal of Shortest-Job-First (SJF) scheduling?
In Round Robin scheduling, how does an increase in the time quantum affect the waiting time of processes with long CPU burst times?
In Round Robin scheduling, how does an increase in the time quantum affect the waiting time of processes with long CPU burst times?
What is the main goal of high-level scheduling in batch systems?
What is the main goal of high-level scheduling in batch systems?
What is a critical issue related to threading and signal handling in threads?
What is a critical issue related to threading and signal handling in threads?
What are the program behavior characteristics mentioned in the text?
What are the program behavior characteristics mentioned in the text?
What is the primary concern regarding the semantics of fork() and exec() system calls in threading?
What is the primary concern regarding the semantics of fork() and exec() system calls in threading?
______ issues include semantics of fork() and exec() system calls and handling of global variables like errno and malloc().
______ issues include semantics of fork() and exec() system calls and handling of global variables like errno and malloc().
Conflicts between threads over the use of global variables can occur, potentially leading to errors and ______.
Conflicts between threads over the use of global variables can occur, potentially leading to errors and ______.
Scheduling algorithm goals include high, intermediate, and ______ scheduling for batch systems.
Scheduling algorithm goals include high, intermediate, and ______ scheduling for batch systems.
Low-level scheduling, also called CPU scheduling, involves assigning a CPU to a ready process and selection from the ______ queue.
Low-level scheduling, also called CPU scheduling, involves assigning a CPU to a ready process and selection from the ______ queue.
Program behavior characteristics include CPU-I/O burst cycles, CPU/IO cycles, and histogram of CPU burst ______.
Program behavior characteristics include CPU-I/O burst cycles, CPU/IO cycles, and histogram of CPU burst ______.
FCFS scheduling is ________ and uses FIFO queues
FCFS scheduling is ________ and uses FIFO queues
Shortest-Job-First (SJF) scheduling aims to schedule the process with the ________ next CPU burst
Shortest-Job-First (SJF) scheduling aims to schedule the process with the ________ next CPU burst
Priority scheduling may lead to ________, and aging can be used as a solution to the problem
Priority scheduling may lead to ________, and aging can be used as a solution to the problem
Determining the length of the next CPU burst involves guessing based on history using ________ averaging
Determining the length of the next CPU burst involves guessing based on history using ________ averaging
Priority scheduling can be used in both ________ and interactive systems, with each job assigned a priority
Priority scheduling can be used in both ________ and interactive systems, with each job assigned a priority
Multiple processes are executed concurrently with CPU ______ among them
Multiple processes are executed concurrently with CPU ______ among them
Principal events causing process creation include system initialization, process creation system execution, user request, and ______ job initiation
Principal events causing process creation include system initialization, process creation system execution, user request, and ______ job initiation
In UNIX, the fork() system call creates a new process as a clone of the parent process, while execve() system call replaces the process’ memory space with a new ______
In UNIX, the fork() system call creates a new process as a clone of the parent process, while execve() system call replaces the process’ memory space with a new ______
Processes exist in a hierarchy forming a process group or process tree in many operating ______
Processes exist in a hierarchy forming a process group or process tree in many operating ______
Processes are implemented through a process table or process control block (PCB) containing information about computation, memory management, and ______ management
Processes are implemented through a process table or process control block (PCB) containing information about computation, memory management, and ______ management
An operating system executes a variety of programs: – Batch system – jobs – Time-shared systems – user programs or tasks Short definition: A process is a ______.
An operating system executes a variety of programs: – Batch system – jobs – Time-shared systems – user programs or tasks Short definition: A process is a ______.
A program is the code sitting in a file in this terminology. 3 Process Concept Multiple parts – The program code, also called text section – Current activity including program counter register and processor registers – Stack containing temporary data Function parameters, return addresses, local variables – Data section containing global variables – Heap containing memory dynamically allocated during run time (through new and malloc()). 4 Process in Memory Address space of a process (typically ______).
A program is the code sitting in a file in this terminology. 3 Process Concept Multiple parts – The program code, also called text section – Current activity including program counter register and processor registers – Stack containing temporary data Function parameters, return addresses, local variables – Data section containing global variables – Heap containing memory dynamically allocated during run time (through new and malloc()). 4 Process in Memory Address space of a process (typically ______).
The notion of a software process is used in operating systems to express the management and control of such activities. A process is the key concept underlying modern operating system ______.
The notion of a software process is used in operating systems to express the management and control of such activities. A process is the key concept underlying modern operating system ______.
An operating system involves asynchronous, and sometimes parallel/concurrent, activities. The notion of a software process is used in operating systems to express the management and control of such activities. A process is the key concept underlying modern operating system ______.
An operating system involves asynchronous, and sometimes parallel/concurrent, activities. The notion of a software process is used in operating systems to express the management and control of such activities. A process is the key concept underlying modern operating system ______.
Multithreading involves creating a new ______ for each HTTP request
Multithreading involves creating a new ______ for each HTTP request
Threads offer benefits such as low overhead context switching, resource sharing, economy, and utilization of ______ architectures
Threads offer benefits such as low overhead context switching, resource sharing, economy, and utilization of ______ architectures
In a single process, a thread shares its code section, data section, and OS resources with other ______
In a single process, a thread shares its code section, data section, and OS resources with other ______
Thread operations include creation, blocking, unblocking, and ______, similar to processes
Thread operations include creation, blocking, unblocking, and ______, similar to processes
Multiple threaded processes enhance throughput and performance by allowing one thread to run while another is ______ and waiting
Multiple threaded processes enhance throughput and performance by allowing one thread to run while another is ______ and waiting
Each process in Round Robin scheduling gets 1/n of the CPU time in chunks of at most ______ time units at once.
Each process in Round Robin scheduling gets 1/n of the CPU time in chunks of at most ______ time units at once.
Short CPU burst processes in Round Robin scheduling get their chance and exit the queue quickly when they are done, such as ______ tasks.
Short CPU burst processes in Round Robin scheduling get their chance and exit the queue quickly when they are done, such as ______ tasks.
If the burst times for processes P1, P2, P3, and P4 in Round Robin scheduling with time quantum 20 are 25, 15, 30, and 20 respectively, the completion time of process P3 is ______.
If the burst times for processes P1, P2, P3, and P4 in Round Robin scheduling with time quantum 20 are 25, 15, 30, and 20 respectively, the completion time of process P3 is ______.
In Round Robin scheduling, an increase in the time quantum ______ the waiting time of processes with long CPU burst times.
In Round Robin scheduling, an increase in the time quantum ______ the waiting time of processes with long CPU burst times.
In Round Robin scheduling, if there are 4 processes in the ready queue and the time quantum is 10 milliseconds, the maximum time any process has to wait to get CPU time is ______.
In Round Robin scheduling, if there are 4 processes in the ready queue and the time quantum is 10 milliseconds, the maximum time any process has to wait to get CPU time is ______.
Study Notes
CPU Scheduling Algorithms Overview
- First Come First Serve (FCFS) policy allocates CPU to the first arriving process
- FCFS scheduling is non-preemptive and uses FIFO queues
- FCFS performance metric is the average waiting time
- FCFS scheduling example demonstrates Gantt chart visualization and average waiting time calculation
- Convoy effect in FCFS occurs when short processes wait behind long processes
- Shortest-Job-First (SJF) scheduling aims to schedule the process with the shortest next CPU burst
- SJF has non-preemptive and preemptive versions, with preemptive being known as Shortest-Remaining-Time-First (SRTF)
- Non-preemptive SJF example shows Gantt chart visualization and average waiting time calculation
- Preemptive SJF example demonstrates Gantt chart visualization and average waiting time calculation
- Determining the length of the next CPU burst involves guessing based on history using exponential averaging
- Priority scheduling can be used in both batch and interactive systems, with each job assigned a priority
- Priority scheduling may lead to starvation, and aging can be used as a solution to the problem.
Operating System Scheduling and Threading
- Solaris 2 and Windows NT/2000 with ThreadFiber package allow the operating system to create a sufficient number of kernel threads.
- Threading issues include semantics of fork() and exec() system calls and handling of global variables like errno and malloc().
- Signal handling in threads raises the question of which thread should catch the signals, especially in user-threads.
- Conflicts between threads over the use of global variables can occur, potentially leading to errors and suspensions.
- Processes and thread scheduling involves scheduling objectives for batch, interactive, and real-time systems.
- Scheduling objectives include enforcing fairness, priorities, equipment utilization, and preference to processes exhibiting good behavior.
- Performance terms associated with scheduling include fairness, CPU and resource utilization, throughput, turnaround time, waiting time, and response time.
- Program behavior characteristics include CPU-I/O burst cycles, CPU/IO cycles, and histogram of CPU burst times.
- Scheduling algorithm goals include high, intermediate, and low-level scheduling for batch systems.
- High-level scheduling involves selecting a mix of CPU-bound and I/O-bound jobs and alternate selection criteria.
- Intermediate scheduling involves temporarily suspending or resuming jobs to smooth fluctuations in system load.
- Low-level scheduling, also called CPU scheduling, involves assigning a CPU to a ready process and selection from the ready queue.
Multithreading: Types, Models, and Usage
- Multithreading involves creating a new process for each HTTP request, but this can lead to high overhead.
- Threads offer benefits such as low overhead context switching, resource sharing, economy, and utilization of multiprocessor architectures.
- In a single process, a thread shares its code section, data section, and OS resources with other threads.
- Thread usage examples include a word processor with three threads for input, reformat, and save, as well as graphics applications like augmented reality.
- Thread operations include creation, blocking, unblocking, and termination, similar to processes.
- Threads go through states like ready, blocked, running, and terminated, and they are considered cooperating with no protection among threads.
- Multiple threaded processes enhance throughput and performance by allowing one thread to run while another is blocked and waiting.
- Extensive sharing in threads makes CPU switching and thread creation inexpensive compared to heavyweight processes.
- There are different types of thread implementations including kernel-supported threads, user-level threads, and hybrid approaches.
- User-level threads are managed by a user-level threads library, reducing context switch times and eliminating kernel overhead.
- Disadvantages of user-level threads include the potential for any user-level thread to block the entire task if the kernel is single threaded.
- Kernel threads are supported and managed by the kernel, allowing explicit scheduling and parallel processing, but with less control over scheduling and higher overhead compared to user-level threads.
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Description
Test your knowledge of CPU scheduling algorithms with this quiz. Explore First Come First Serve (FCFS), Shortest-Job-First (SJF), and Priority scheduling, and learn about their features, performance metrics, and potential issues. Dive into examples with Gantt chart visualizations and average waiting time calculations to deepen your understanding of these essential algorithms.
