api: YAML JSON TOON Database
version: 1.0.0
format: json
dataset:
  slug: cpu-scheduling-algorithms
  title: CPU Scheduling Algorithms
  description: Algorithms used by the OS to allocate CPU time.
  summary: "The classic CPU scheduling algorithms, each marked preemptive or non-preemptive with a one-line description, from first-come first-served to multilevel feedback queues, plus real-time schedulers such as earliest-deadline-first and the Linux Completely Fair Scheduler."
  use_when[2]: "You need to compare scheduling policies by fairness, responsiveness and starvation risk.",You are explaining how an OS divides CPU time among processes.
  caveats[2]: Textbook algorithms assume known burst times; real systems estimate them or ignore them.,"Real schedulers combine ideas, for example priority queues with time slices and aging to avoid starvation."
  related[3]: process-management,deadlock-handling,memory-management
  category: Operating Systems
  category_slug: operating-systems
  tags: "os,scheduling,cpu"
  view_count: 0
  entry_count: 13
  fields[3]{section,field,type,example}:
    data,name,string,First-Come First-Served
    data,type,string,Non-preemptive
    data,description,string,Processes run in arrival order; simple but can …
data[13]{name,type,description}:
  First-Come First-Served,Non-preemptive,Processes run in arrival order; simple but can cause convoy effect.
  Shortest Job First,Non-preemptive,Runs the process with the shortest estimated burst time.
  Shortest Remaining Time First,Preemptive,Preemptive version of SJF.
  Round Robin,Preemptive,Each process gets a fixed time quantum in cyclic order.
  Priority Scheduling,Variable,Highest priority process runs first.
  Multilevel Queue,Non-preemptive queues,Processes assigned to fixed priority queues.
  Multilevel Feedback Queue,Adaptive,Processes move between queues based on behavior and aging.
  Highest Response Ratio Next,Non-preemptive,"Picks the ready process with the highest (waiting time + service time) / service time, which prevents starvation of long jobs."
  Earliest Deadline First,Preemptive,Real-time policy that always runs the task with the nearest deadline; optimal on a single processor when utilization is at most 100%.
  Rate-Monotonic Scheduling,Preemptive,Fixed-priority real-time policy that gives shorter-period tasks higher priority.
  Completely Fair Scheduler,Preemptive,"Linux's general-purpose scheduler for many years, tracking each task's virtual runtime in a red-black tree to share CPU time fairly."
  Lottery Scheduling,Preemptive,"Randomly selects the next process in proportion to the tickets it holds, giving probabilistic proportional share."
  Fair-Share Scheduling,Preemptive,Divides CPU time among users or groups rather than individual processes.