Modern safety-critical systems, such as avionics, tend to be mixed-critical, because integration of different tasks with different assurance requirements can effectively reduce their costs in terms of hardware, at the risk, however to increase the costs for certification, in particular in the context of proving their schedulability. To simplify the certification costs such systems use Time Triggered (TT) scheduling paradigm, and a generalization of the Time Triggered (TT) scheduling paradigm Single Time Table per Mode (STTM), is a promising scheduling approach as, compared to priority-based algorithms. In the present paper we present a state-of-the art STTM algorithm which works optimally on single core and shows good preliminary results for multi-cores.