Description of execution time dynamics for a set of concurrent real-time tasks

A Real-time System (RTS) implemented in a digital computer interacts with the physical world through knowledge variables (sensors, actuators, Analogical - Digital, and Digital-Analogical convertors) processing its requirements through real-time tasks (Ji: i∈Z+). Each Ji is formed by a set of instances {ji,k: i, k∈Z+, i is the task index, k is the instance index} with at least three time constraints: arrival, execution and, interval times (Li,k, Ci,k, Di,k). The execution time identification ˆCi ,k , is based on Instrumental Variable parameter estimation and the recursive state space ARMA model. The execution times were measured experimentally using a Real-time Operative System QNX 6.5 Neutrino in an Intel Core i7 processor with a speed of 2.66 GHz. This paper presents a state of the art real-time task model, execution time measurements, an Instrumental Variable parameter estimator on recursive state space identification, experimentation and, results.