Run-to-completion scheduling or nonpreemptive scheduling is a
scheduling
A schedule or a timetable, as a basic time-management tool, consists of a list of times at which possible tasks, events, or actions are intended to take place, or of a sequence of events in the chronological order in which such things are ...
model in which each task runs until it either finishes, or explicitly yields control back to the scheduler.
Run to completion systems typically have an
event queue
In computer science, message queues and mailboxes are software-engineering components typically used for inter-process communication (IPC), or for inter- thread communication within the same process. They use a queue for messaging – the ...
which is serviced either in strict order of admission by an
event loop In computer science, the event loop is a programming construct or design pattern that waits for and dispatches events or messages in a program. The event loop works by making a request to some internal or external "event provider" (that generally ...
, or by an
admission scheduler
In computing, scheduling is the action of assigning ''resources'' to perform ''tasks''. The ''resources'' may be processors, network links or expansion cards. The ''tasks'' may be threads, processes or data flows.
The scheduling activity is ca ...
which is capable of scheduling events out of order, based on other constraints such as
deadlines.
Some
preemptive multitasking
In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemp ...
scheduling systems behave as run-to-completion schedulers in regard to scheduling tasks at one particular
process priority
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic.
Things called a process include:
Business and management
*Business process, activities that produce a specific se ...
level, at the same time as those processes still preempt other lower priority tasks and are themselves preempted by higher priority tasks.
See also
*
Deadline scheduling
*
Preemptive multitasking
In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemp ...
*
Cooperative multitasking
Cooperative multitasking, also known as non-preemptive multitasking, is a style of computer multitasking in which the operating system never initiates a context switch from a running process to another process. Instead, in order to run multiple ...
References
Algorithms
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