In operating systems, the CPU scheduler that selects processes from the ready queue for execution on the processor is also known as which type of scheduler?

Introduction / Context:
Operating systems use different kinds of schedulers to manage processes at various stages of their life cycle. The CPU scheduler is responsible for deciding which process in the ready queue should be given the CPU next. Understanding the relationship between the terms CPU scheduler, job scheduler, and short term scheduler is a key part of operating systems theory that often appears in exam questions.

Given Data / Assumptions:

• The specific scheduler mentioned is the CPU scheduler.
• It selects processes from the ready queue for execution.
• The options list several types of schedulers used in operating systems.

Concept / Approach:
In classical operating systems terminology, the short term scheduler, also called the CPU scheduler, decides which of the processes in the ready state should be moved to the running state. A job scheduler or long term scheduler controls admission of new jobs into the system, and a medium term scheduler may swap processes in and out of memory. The key phrase ready queue and direct control of the CPU indicate that the question refers to the short term scheduler, which operates very frequently.

Step-by-Step Solution:
Step 1: Recall that the short term scheduler is responsible for selecting processes from the ready queue and allocating the CPU. Step 2: Recognise that job scheduler usually refers to the long term scheduler, which decides which jobs are admitted to the system for processing. Step 3: Note that resource scheduler is a more general phrase and is not the standard formal name for the CPU scheduler in most textbooks. Step 4: Understand that the CPU scheduler is often described explicitly as the short term scheduler that runs very frequently. Step 5: Therefore, identify short-term scheduler as the correct synonym for CPU scheduler in this context.

Verification / Alternative check:
Operating systems references often present a hierarchy of schedulers: long term for job admission, medium term for swapping, and short term for CPU dispatch. In diagrams, the short term scheduler sits directly between the ready queue and the running state, controlling which process gets the CPU. When authors refer to the CPU scheduler, they are referring to this short term scheduler. This confirms the equivalence and validates short-term scheduler as the correct answer.

Why Other Options Are Wrong:
Job scheduler: This is wrong because job scheduler usually means the long term scheduler that decides which jobs are brought into memory from secondary storage, not which ready process gets immediate CPU time.
Resource scheduler: This is wrong because it is a vague term and not the precise textbook name for the scheduler that selects ready processes for the CPU.
Process scheduler: This is wrong as the best answer because while some may informally say process scheduler, the formal term used to describe the CPU scheduler that operates frequently is short term scheduler.

Common Pitfalls:
Students sometimes confuse long term and short term schedulers because both relate to processes. Another pitfall is thinking that job scheduler and CPU scheduler are the same because they both involve scheduling. The key is to remember where in the life cycle the scheduler operates. If the scheduler is choosing among ready processes for immediate CPU usage, it is the short term scheduler, also known as the CPU scheduler.

Final Answer:
The CPU scheduler that selects processes from the ready queue is also known as the Short-term scheduler.