ITPEC FE Morning October 2020 Question 16

Which of the following is an appropriate description of the dispatcher in an operating system?

a)A function in which multiple tasks appear to be running simultaneously on a single processorb)The allocation of the right to use a processor for a ready processc)The context that is the information required for process executiond)The determination of the order of execution for each proces

Explanation

Giving the processor to a process that is ready — the dispatcher hands the CPU to the process the scheduler selected, moving it from ready to running.

Dispatching restores the chosen process's saved context (registers, program counter) and transfers control to it. Deciding which process should run next is the job of the scheduler; the dispatcher carries the decision out.

Answer (b)

Why not others:

•(a) — tasks that appear to run at once on one processor describe multitasking (multiprogramming by time sharing)
•(c) — the information needed to run a process is its context, which is saved in the process control block; the dispatcher uses it but is not it
•(d) — deciding the order of execution is scheduling

Key rule: The scheduler chooses which ready process runs next; the dispatcher switches the context and actually gives it the CPU.

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