12 Questions
What is the main difference between multiprogramming and true simultaneous execution of different programs?
In multiprogramming, the OS executes parts of different programs sequentially.
How did single processor computers operate before the introduction of multiprogramming?
They could not run more than one program at a time.
What issue did multiprogramming aim to address in single processor computers?
CPU sitting idle during I/O operations.
How does the operating system handle CPU resources in a multiprogramming environment?
Assigns CPU resources to each program in rotation as resources become available.
How does multiprogramming create the illusion of parallel execution to the user?
By executing parts of different programs sequentially.
What was a significant limitation of single processor computers before multiprogramming was introduced?
Inability to handle I/O operations efficiently.
What is the purpose of context switching in an operating system?
To manage CPU resources between programs during I/O operations
In cooperative multiprogramming, when is context switching initiated?
When a program releases control of resources
What problem can occur in cooperative multiprogramming if a program does not release CPU resources?
A program might monopolize CPU resources
How does preemptive multiprogramming differ from cooperative multiprogramming?
It forcibly takes control from programs to switch tasks
What is the role of the operating system in managing CPU resources during I/O operations?
Reassigning CPU resources during ongoing I/O operations
Why is cooperative multiprogramming seldom used today?
It leads to inefficient CPU resource allocation
Study Notes
Multiprogramming
- A rudimentary form of parallel processing in which several programs run at the same time on a uniprocessor system.
- Only one processor is present, but the operating system (OS) executes part of one program, then part of another, creating an illusion of simultaneous execution.
Advantages of Multiprogramming
- Addresses the issue of underutilized processor resources and application delays caused by single-program execution.
- Allows multiple programs to load into memory and run each one in rotation as CPU resources become available.
How Multiprogramming Works
- The OS assigns CPU resources to a program until it launches into I/O operations.
- Then, the OS assigns CPU resources to another program already loaded into memory.
- Context switching is used to preserve a program's state in memory and enable quick access when switching between programs and CPU assignments.
Types of Multiprogramming
- Cooperative multiprogramming: initiated by programs themselves, where they release control of resources to the OS.
- Rarely used today due to the risk of programs monopolizing CPU resources.
- Preemptive multiprogramming: the OS initiates context switching, ensuring efficient allocation of CPU resources.
Goals of Multiprogramming
- Maximize CPU time by efficient allocation of resources and minimizing idleness.
Learn about the concept of multiprogramming in operating systems, where multiple programs run on a uniprocessor system by sharing the processor's time. Discover how the operating system handles the execution of programs in a pseudo-parallel manner.
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