Library prosa.model.processor.ideal

From mathcomp Require Import all_ssreflect.
Require Export prosa.behavior.all.

The Ideal Uniprocessor Model

In this module, we define a central piece of the Prosa model: the notion of an ideal uniprocessor state. The word "ideal" here refers to the complete absence of runtime overheads or any other complications. In an ideal uniprocessor schedule, there are only two possible cases: at a given time, either a specific job is scheduled and makes unit-progress, or the processor is idle. To model this, we simply reuse the standard option type from the Coq standard library.

Section State.

Consider any type of jobs.
  Variable Job: JobType.

We connect the notion of an ideal processor state with the generic interface for the processor-state abstraction in Prosa by declaring a so-called instance of the ProcessorState typeclass.

End State.

Idle Instants

In this section, we define the notion of idleness for ideal uniprocessor schedules.
Section IsIdle.

Consider any type of jobs...
  Context {Job : JobType}.
  Variable arr_seq : arrival_sequence Job.

... and any ideal uniprocessor schedule of such jobs.
  Variable sched : schedule ((*ideal*)processor_state Job).

We say that the processor is idle at time t iff there is no job being scheduled.
  Definition is_idle (t : instant) := sched t == None.

End IsIdle.