780 research outputs found
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
Predictability of Fixed-Job Priority Schedulers on Heterogeneous Multiprocessor Real-Time Systems
The multiprocessor Fixed-Job Priority (FJP) scheduling of real-time systems
is studied. An important property for the schedulability analysis, the
predictability (regardless to the execution times), is studied for
heterogeneous multiprocessor platforms. Our main contribution is to show that
any FJP schedulers are predictable on unrelated platforms. A convenient
consequence is the fact that any FJP schedulers are predictable on uniform
multiprocessors
Gang FTP scheduling of periodic and parallel rigid real-time tasks
In this paper we consider the scheduling of periodic and parallel rigid
tasks. We provide (and prove correct) an exact schedulability test for Fixed
Task Priority (FTP) Gang scheduler sub-classes: Parallelism Monotonic, Idling,
Limited Gang, and Limited Slack Reclaiming. Additionally, we study the
predictability of our schedulers: we show that Gang FJP schedulers are not
predictable and we identify several sub-classes which are actually predictable.
Moreover, we extend the definition of rigid, moldable and malleable jobs to
recurrent tasks
Schedulability analysis of global scheduling algorithms on multiprocessor platforms
This paper addresses the schedulability problem of periodic and sporadic real-time task sets with constrained deadlines preemptively scheduled on a multiprocessor platform composed by identical processors. We assume that a global work-conserving scheduler is used and migration from one processor to another is allowed during a task lifetime. First, a general method to derive schedulability conditions for multiprocessor real-time systems will be presented. The analysis will be applied to two typical scheduling algorithms: earliest deadline first (EDF) and fixed priority (FP). Then, the derived schedulability conditions will be tightened, refining the analysis with a simple and effective technique that significantly improves the percentage of accepted task sets. The effectiveness of the proposed test is shown through an extensive set of synthetic experiments
Schedulability analysis of global scheduling algorithms on multiprocessor platforms
This paper addresses the schedulability problem of periodic and sporadic real-time task sets with constrained deadlines preemptively scheduled on a multiprocessor platform composed by identical processors. We assume that a global work-conserving scheduler is used and migration from one processor to another is allowed during a task lifetime. First, a general method to derive schedulability conditions for multiprocessor real-time systems will be presented. The analysis will be applied to two typical scheduling algorithms: earliest deadline first (EDF) and fixed priority (FP). Then, the derived schedulability conditions will be tightened, refining the analysis with a simple and effective technique that significantly improves the percentage of accepted task sets. The effectiveness of the proposed test is shown through an extensive set of synthetic experiments
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