IIIE   20352
INSTITUTO DE INVESTIGACIONES EN INGENIERIA ELECTRICA "ALFREDO DESAGES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Efficient on-line schedulability test for feedback scheduling of
soft real-time tasks under fixed-priority
Autor/es:
RODRIGO SANTOS; GIUSEPPE LIPARI; ENRICO BINI
Lugar:
Saint Louis (MO) EEUU
Reunión:
Conferencia; 14th IEEE Real-Time and Embedded Technology and Applications Symposium; 2008
Institución organizadora:
IEEE
Resumen:
When dealing with soft real-time tasks with highly variable execution times in open systems, an approach that is becoming popular is to use feedback scheduling techniques to dynamically adapt the bandwidth reserved to each task. According to this model, each task is assigned an adaptive reservation, with a variable budget and a constant period. The response times of the jobs of the task are monitored and if different from expected (i.e. much larger or much shorter than the task relative deadline), a feedback control law adjusts the reservation budget accordingly. However, when the feedback law algorithm demands an increase of the reservation budget, the system must run a schedulability test to check if there is enough spare bandwidth to accommodate such increase. The schedulability test must be very efficient, as it may be performed at each budget update, i.e. potentially at each instance of a task. In this paper, we tackle the problem of performing an efficient on-line schedulability test for Resource Reservation systems implemented through the Sporadic Server on Fixed Priority scheduling. We propose five different tests with different complexity and performance. In particular, we propose a novel on-line test, called emph{Spare Pot algorithm} which shows a good cost/performance ratio.