Dealing with overloading in tasks scheduling

Recently, there has been an increasing interest in programming models of real-time systems and approaches of flexible scheduling for dealing with situations of transient overloading, which can occur in nondeterministic environments. This paper presents the (p+i, k)-firm approach that can be seen as a combination and generalization of imprecise computing and of deadline (m,k)-firm. This approach extends the (m,k)-firm concept allowing a task to execute in an imprecise way, obtaining better results than a deadline missing. The approach seeks to establish a compromise between avoiding temporal failures and maximizing the quality (cumulative value). A battery of tests was developed to evaluate the approach and its capacity to reduce the probability of dynamic failures and to obtain a smooth degradation in overload conditions.