We suggest a slightly simplified model, focusing on the assignment of shared continuous resources to the processors. The job assignment to processors and the ordering of the jobs have already been fixed. Our work shows that finding an optimal solution is NP-hard if the number of processors is a part of the input, even in the case of unit size jobs. On the positive side, we can give an optimal algorithms for two processors and prove that "balanced" schedules yield a $2-1/m$-approximation. Such schedules can be computed by a simple greedy algorithm, for which this bound is tight.