3 research outputs found
Scheduling of Hard Real-Time Multi-Thread Periodic Tasks
In this paper we study the scheduling of parallel and real-time recurrent
tasks. Firstly, we propose a new parallel task model which allows recurrent
tasks to be composed of several threads, each thread requires a single
processor for execution and can be scheduled simultaneously. Secondly, we
define several kinds of real-time schedulers that can be applied to our
parallel task model. We distinguish between two scheduling classes:
hierarchical schedulers and global thread schedulers. We present and prove
correct an exact schedulability test for each class. Lastly, we also evaluate
the performance of our scheduling paradigm in comparison with Gang scheduling
by means of simulations
On the periodic behavior of real-time schedulers on identical multiprocessor platforms
This paper is proposing a general periodicity result concerning any
deterministic and memoryless scheduling algorithm (including
non-work-conserving algorithms), for any context, on identical multiprocessor
platforms. By context we mean the hardware architecture (uniprocessor,
multicore), as well as task constraints like critical sections, precedence
constraints, self-suspension, etc. Since the result is based only on the
releases and deadlines, it is independent from any other parameter. Note that
we do not claim that the given interval is minimal, but it is an upper bound
for any cycle of any feasible schedule provided by any deterministic and
memoryless scheduler
Exact Schedulability Tests for Real-Time Scheduling of Periodic Tasks on Unrelated Multiprocessor Platforms
In this paper, we study the global scheduling of periodic task systems on unrelated multiprocessor platforms. We first show two general properties which are well known for uniprocessor platforms and which are also true for unrelated multiprocessor platforms: (i) under few and not so restrictive assumptions, we prove that feasible schedules of periodic task systems are periodic starting from some point in time with a period equal to the least common multiple of the task periods and (ii) for the specific case of synchronous periodic task systems, we prove that feasible schedules repeat from their origin. We then present our main result: we characterize, for task-level fixed-priority schedulers and for asynchronous constrained or arbitrary deadline periodic task models, upper bounds of the first time-instant where the schedule repeats. For task-level fixed-priority schedulers, based on the upper bounds and the predictability property, we provide exact schedulability tests for asynchronous constrained or arbitrary deadline periodic task sets. Finally, we provide an exact schedulability test as well for the job-level fixed-priority Earliest Deadline First (EDF) scheduler, for which such an upper bound is unknown. © 2010 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe