Operating systemsLesson 3 of 3 in the course Processes and scheduling

Operating-System Scheduling: Algorithms, Policies, and Kernel Implementations

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Scheduling is how a computer system decides which tasks receive resources and when. It underlies multitasking, resource sharing, and predictable system behavior.

In computing, scheduling is the assignment of resources to tasks. Resources can include processors, network links, or expansion cards; tasks can include threads, processes, or data flows. A scheduler is the mechanism that makes these allocation decisions.

All flashcards

First come, first served (FCFS)
Runs processes in arrival order; a long job at the front can cause the convoy effect.
Shortest remaining time first (SRTF)
Chooses the process with the least estimated processing time remaining and can preempt the current process.
Priority scheduling
Favors higher-priority processes; continual higher-priority arrivals can leave lower-priority processes waiting indefinitely.
Round-robin scheduling
Gives processes turns using fixed time slices; smaller slices improve responsiveness but increase switching overhead.
Earliest deadline first (EDF)
Selects the task whose deadline is closest when a scheduling decision occurs.

Quiz questions

  1. Which operating-system scheduler chooses the next ready, in-memory process to receive the CPU?Answer: The short-term scheduler
  2. What is the medium-term scheduler primarily responsible for?Answer: Moving processes between main memory and secondary storage
  3. What does dispatch latency measure?Answer: The time needed to stop one process and start another
  4. What does it mean for a scheduler to be work-conserving?Answer: It tries to keep its resources busy when submitted work is ready.
  5. How do open-shop and flow-shop scheduling differ?Answer: Open-shop station order is flexible; flow-shop station order is predetermined.

Based on the Wikipedia article Scheduling (computing), licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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