Leo Hatvani

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In this paper, we present a tool for performing trade-off analysis of Quality-of-Service attributes of design solutions resulted from architectural, behavioral, or deployment changes in service-oriented systems. The tool allows for comparing the performance, reliability, and maintainability of such solutions, in an attempt to compute the optimal one with(More)
To combine the relative strengths of fully preemptive and non-preemptive fixed priority scheduling, we can use limited preemptive scheduling methods. One such method is fixed-priority threshold scheduling (FPTS). This approach defines dual priorities for every task, a priority assigned to the inactive jobs and an equal or a higher one, called preemption(More)
Adaptive embedded systems are systems that must be capable to dynamically reconfigure in order to adapt to e.g., changes in available resources, useror application driven mode changes, or modified quality of service requirements. The possibility to adapt provides flexibility that extends the area of operation of embedded systems and potentially reduces(More)
Fixed priority preemption threshold scheduling (FPTS) may significantly improve the schedulability ratio of task sets compared to both fixed-priority pre-emptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). Moreover, FPTS reduces stack memory requirements compared to FPPS. Unfortunately, the scheduling policy defined by the(More)
Most embedded systems need to continually function in unpredictable environments. One way to achieve high dependability is to make the system adaptive to changes, if possible, without sacrificing maintainability. To be able to reason about adaptivity, one needs a modeling and analysis framework suitable for adaptive systems. Recently, we have introduced(More)
Fixed-priority preemption-threshold scheduling (FPTS) is a generalization of fixed-priority preemptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). Since FPPS and FPNS are incomparable in terms of potential schedulability, FPTS has the advantage that it can schedule any task set schedulable by FPPS or FPNS and some that are not(More)
Adjusting to resource changes, dynamic environmental conditions, or new usage modes are some of the reasons why real-time embedded systems need to be adaptive. This requires a rigorous framework for designing such systems, to ensure that the adaptivity does not result in invalidating the system’s real-time constraints. To address this need, we have recently(More)
Fixed-priority preemption threshold scheduling (FPTS) is a limited preemptive scheduling scheme that generalizes both fixed-priority preemptive scheduling (FPPS) and fixed-priority non-preemptive scheduling (FPNS). By increasing the priority of tasks as they start executing it reduces the set of tasks that can preempt any given task. A subset of FPTS task(More)
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