Major Commit: Suspension-aware Scheduling

1) Definition of a generic model for job suspensions based on
   received service (e.g., job j_1 should suspend for 4ms as
   soon as service reaches 5ms).

2) Definition of the dynamic suspension model (i.e., cumulative
   suspension of job j_1 <= X).

3) Analysis of suspension-aware scheduling by inflation of job
   costs (via schedule reduction). In the literature, this is
   called suspension-oblivious analysis.

4) Analysis of suspension-aware scheduling by adjusting job
   jitter (via schedule reduction).

5) Proof of (weak) sustainability of job costs under suspension-aware
   scheduling. We show that if we increase the costs of all jobs while
   reducing their suspension times in a certain way, the response times
   of all jobs do not decrease.

   This has an important implication regarding worst-case schedules: if
   some schedulability analysis already accounts for the fact that job
   suspension times can vary from 0 to the task suspension bound, then
   it's perfectly safe to assume that jobs execute for their WCET.

6) Proof of sustainability of the cost of a single job under
   suspension-aware scheduling. That is, we show that increasing the
   cost of a single job does not reduce its own response time.
   (Note that this is a very basic result that applies to many
   work-conserving, JLFP schedulers. We don't claim anything about
   the response time of other jobs.)

implementation/global/jitter/schedule.v

@@ -98,7 +98,7 @@ Module ConcreteScheduler.
     Variable num_cpus: nat.
     Hypothesis H_at_least_one_cpu: num_cpus > 0.
 
-    (* Let arr_seq be any job arrival sequence with consistent, non-duplicate arrivals. *)
+    (* Let arr_seq be any job arrival sequence with consistent, duplicate-free arrivals. *)
     Variable arr_seq: arrival_sequence Job.
     Hypothesis H_arrival_times_are_consistent: arrival_times_are_consistent job_arrival arr_seq.
     Hypothesis H_arrival_sequence_is_a_set: arrival_sequence_is_a_set arr_seq.

implementation/uni/basic/schedule.v

@@ -89,7 +89,7 @@ Module ConcreteScheduler.
     Variable job_arrival: Job -> time.
     Variable job_cost: Job -> time.
 
-    (* Let arr_seq be any job arrival sequence with consistent, non-duplicate arrivals. *)
+    (* Let arr_seq be any job arrival sequence with consistent, duplicate-free arrivals. *)
     Variable arr_seq: arrival_sequence Job.
     Hypothesis H_arrival_times_are_consistent: arrival_times_are_consistent job_arrival arr_seq.
     Hypothesis H_arrival_sequence_is_a_set: arrival_sequence_is_a_set arr_seq.