In this paper we consider the problem of optimal task allocation and scheduling in embedded real-time systems. This problem is far from trivial due to the wide range of complex constraints that typically appear in this type of systems. We therefore address this problem using constraint programming due to its expressive, yet powerful features. Our work includes an evaluation of different search heuristics, such as variable-value orderings and symmetry exclusion, for this particular problem domain. It is shown that by using search configurations appropriate for the problem, the average search complexity can be reduced by as much as an order of magnitude.