Uniprocessor Scheduling

Introduction:

Uniprocessor Scheduling gives you more focusing for processes in operating system, so you have to understand all tasks of processes.

In a multiprogramming system, multiple processes exist concurrently in main memory. Each process alternates between using a processor and waiting for some event to occur, such as the completion of an I/O operation. The processor or processors are kept busy by executing one process while the others wait.

This video help you to know how operating system processes scheduling

 

Types of Processor Scheduling :

Long-Term Scheduling

The long-term scheduler determines which programs are admitted to the system for processing. Thus, it controls the degree of multiprogramming. Once admitted, a job or user program becomes a process and is added to the queue for the short-term scheduler. In some systems, a newly created process begins in a swapped-out condition, in which case it is added to a queue for the medium-term scheduler.

Medium-Term Scheduling

Medium-term scheduling is part of the swapping function. The issues involved are discussed in Chapters 3, 7, and 8.Typically, the swapping-in decision is based on the need to manage the degree of multiprogramming. On a system that does not use virtual memory, memory management is also an issue. Thus, the swapping-in decision will consider the memory requirements of the swapped-out processes.

Short-Term Scheduling

In terms of frequency of execution, the long-term scheduler executes relatively infrequently and makes the coarse-grained decision of whether or not to take on a new process and which one to take. The medium-term scheduler is executed somewhat more frequently to make a swapping decision. The short-term scheduler, also known as the dispatcher, executes most frequently and makes the fine-grained decision of which process to execute next.

The short-term scheduler is invoked whenever an event occurs that may lead to the blocking of the current process or that may provide an opportunity to preempt a currently running process in favor of another. Examples of such events include

• Clock interrupts

•  I/O interrupts

•  Operating system calls

• Signals (e.g., semaphores)

Question and answer

Instructions that tell the computer what to do. Another name for software

(A) programs

(B) CPU

(C) options

(D) folder

(E) None of these

Correct Answer : A

Now in your comments box down the code you must write five sentences about what did yuo learned With writing yourname and academic number