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Beginner Topic 10 of 51 Operating Systems

CPU Scheduling

Deciding which ready task runs next.

How it works

CPU scheduling decides which ready process or thread runs next and for how long. Goals include high CPU utilization, throughput, low turnaround and waiting time, short response time and fairness. Algorithms such as FCFS, shortest job first, round robin, priority and multilevel feedback queues make different trade-offs, and schedulers may be preemptive or non-preemptive.

Step-by-step walkthrough

  1. Several tasks are ready but there is one CPU.
  2. The scheduler picks task A first.
  3. Then it picks B.
  4. Then C.
  5. Policies decide the order to balance throughput, waiting time and fairness.

Where it is used

Every multitasking OS has a scheduler: Linux uses the completely fair scheduler, while real-time systems use fixed-priority schemes. Tuning priorities and affinities improves latency and throughput for servers and games.

Common pitfall

There is no best algorithm for all workloads. Starvation of low-priority processes, priority inversion and convoy effects are classic problems. Poor time-slice choices make interactive tasks feel sluggish or add overhead. Mixed CPU-bound and I/O-bound workloads need adaptive policies, and aging prevents starvation.

Where it fits in the course

CPU Scheduling is topic 10 of 51 in Operating Systems, rated Beginner. It follows Context Switching. The next topic is Round Robin Scheduling.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Operating Systems quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is CPU Scheduling?
Deciding which ready task runs next. It belongs to Operating Systems and is a beginner-level topic.
Where do people use CPU Scheduling?
Every multitasking OS has a scheduler: Linux uses the completely fair scheduler, while real-time systems use fixed-priority schemes.
What is the most common mistake with CPU Scheduling?
There is no best algorithm for all workloads.
What should I learn before this topic?
Start with Context Switching, the topic just before it in Operating Systems.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Operating Systems quiz.
Is CPU Scheduling hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn CPU Scheduling?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to CPU Scheduling?
Context Switching, Round Robin Scheduling, Threads are closely connected. The full list is in the related topics section of this page.
What should I study after CPU Scheduling?
Continue with Round Robin Scheduling, the next topic in Operating Systems.

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