6,116 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
An SMT-Based Approach to the Formal Analysis of MARTE/CCSL
International audienceMARTE (abbreviated for Modeling and Analysis of Real-Time and Embedded systems) is a UML profile which provides a generalmodeling framework to design and analyze real-time embedded systems. CCSL (abbreviated for Clock Constraint Specification Language) is aformal language companion to MARTE, used to specify the constraints between the occurrences of events in real-time embedded systems. Many approaches have been proposed to the formal analysis of CCSL such as simulation and model checking. We propose in this paper an SMT-based approach to the formal analysis of CCSL. It is well-known that the SMT-based approach can effectively overcome the state-explosion problem for model checking, and can also be used for theorem proving. The latter feature allows us to prove the invalidity of CCSL constraints, which most of the existing approaches lack. We implement the proposed approach in a prototype tool clyzer on top of K framework and use Z3 as theunderlying SMT solver
Four payment models for the multi-mode resource constrained project scheduling problem with discounted cash flows
In this paper, the multi-mode resource constrained project scheduling problem with discounted cash flows is considered. The objective is the maximization of the net present value of all cash flows. Time value of money is taken into consideration, and cash in- and outflows are associated with activities and/or events. The resources can be of renewable, nonrenewable, and doubly constrained resource types. Four payment models are considered: Lump sum payment at the terminal event, payments at prespecified event nodes, payments at prespecified time points and progress payments. For finding solutions to problems proposed, a
genetic algorithm (GA) approach is employed, which uses a special crossover operator that can exploit the multi-component nature of the problem. The models are investigated at the hand of an example problem. Sensitivity analyses are performed over the mark up and the discount rate. A set of 93 problems from literature are solved under the four different payment models and resource type combinations with the GA approach employed resulting in satisfactory computation times. The GA approach is compared with a domain specific heuristic for the lump sum payment case with renewable resources and is shown to outperform it
A Survey of Pipelined Workflow Scheduling: Models and Algorithms
International audienceA large class of applications need to execute the same workflow on different data sets of identical size. Efficient execution of such applications necessitates intelligent distribution of the application components and tasks on a parallel machine, and the execution can be orchestrated by utilizing task-, data-, pipelined-, and/or replicated-parallelism. The scheduling problem that encompasses all of these techniques is called pipelined workflow scheduling, and it has been widely studied in the last decade. Multiple models and algorithms have flourished to tackle various programming paradigms, constraints, machine behaviors or optimization goals. This paper surveys the field by summing up and structuring known results and approaches
Switched max-plus linear-dual inequalities: cycle time analysis and applications
P-time event graphs are discrete event systems suitable for modeling
processes in which tasks must be executed in predefined time windows. Their
dynamics can be represented by max-plus linear-dual inequalities (LDIs), i.e.,
systems of linear dynamical inequalities in the primal and dual operations of
the max-plus algebra. We define a new class of models called switched LDIs
(SLDIs), which allow to switch between different modes of operation, each
corresponding to a set of LDIs, according to a sequence of modes called
schedule. In this paper, we focus on the analysis of SLDIs when the considered
schedule is fixed and either periodic or intermittently periodic. We show that
SLDIs can model a wide range of applications including single-robot
multi-product processing networks, in which every product has different
processing requirements and corresponds to a specific mode of operation. Based
on the analysis of SLDIs, we propose algorithms to compute: i. minimum and
maximum cycle times for these processes, improving the time complexity of other
existing approaches; ii. a complete trajectory of the robot including start-up
and shut-down transients.Comment: 49 pages, 17 figures, journal paper, fixed typo in Remark 3, fixed
formulas in Remarks 3 and
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