1. In a system comprised of at least one application and at least one parameter which affects a behavior of the at least one application, a method for determining a frequency for invoking the at least one application comprising the steps of: estimating a cost which includes overhead resulting from invoking the at least one application; estimating an improvement in the behavior resulting from modifying the at least one parameter based on invoking the at least one application; and selecting the frequency based on the cost and the improvement.