J. Carlos Palencia

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In this paper we present an extension to current schedulability analysis techniques for periodic tasks with offsets, scheduled under a preemptive fixed priority scheduler. Previous techniques allowed only static offsets restricted to being smaller than the task periods. With the extension presented in this paper, we eliminate this restriction and we allow(More)
1 This paper describes a model for representing the temporal and logical elements of real-time applications, called MAST. This model allows a very rich description of the system , including the effects of event or message-based synchronization , multiprocessor and distributed architectures as well as shared resource synchronization. The model is directly(More)
In this paper we present improved techniques for the schedulability analysis of tasks with precedence relations in multiprocessor and distributed systems, scheduled under a preemptive fixed priority scheduler. Recently developed techniques, based on the analysis of tasks with dynamic offsets, take into account the precedence relations between tasks only(More)
Offset-based response time analysis of tasks scheduled with fixed priorities has demonstrated to be a powerful tool to analyze many task models with different kinds of timing constraints, like regular periodic tasks, suspending tasks, distributed systems, tasks with varying priorities, multi-frame models, etc. Offset-based analysis techniques are capable of(More)
1 Hierarchical schedulers are getting increased attention in many research projects because they bring in flexibility, they can take advantage of the best features of different scheduling policies, and allow the composability of applications developed under different scheduling strategies. Most commercial real-time operating systems have an underlying fixed(More)
___________________ This work has been supported in part by the Comisión Interministerial de Ciencia y Tecnología of the Spanish Government, under Grant TAP97-892 In this paper we present an improvement of the schedulability analysis technique for distributed hard realtime systems that allows us to increase the maximum schedulable resource utilization.(More)
___________________ This work has been supported in part by the Comisión Interministerial de Ciencia y Tecnología of the Spanish Government, under Grant TAP94-996 In this paper we investigate into the validity of the Rate Monotonic Analysis techniques for distributed hard real-time systems. A recent paper has shown that the algorithm developed by Tindell(More)
Scheduling theory generally assumes that real-time systems are mostly composed of activities with hard real-time requirements. Many systems are built today by composing different applications or components in the same system, leading to a mixture of many different kinds of requirements with small parts of the system having hard real-time requirements and(More)
The increasing acceptance of the Earliest Deadline First (EDF) scheduling algorithm in industrial environments, together with the continued usage of Fixed Priority (FP) scheduling is leading to heterogeneous systems with different scheduling policies in the same distributed system. Schedulability analysis techniques usually consider the entire system as a(More)
The present paper is focused on hierarchical modeling in monoprocessor real-time systems. In the current scheduling, each system application is isolated through periodic servers. While previous research oriented both local and global schedulers to fixed priorities, this study extends the scheduling to dynamic priorities (EDF). The new analysis consists in(More)