Efficient runtime resource management in heterogeneous Multi-Processor Systems-on-Chip (MPSoCs) for achieving high performance and energy efficiency is one key challenge for system designers. In the past years, several IP blocks have been proposed that implement system-wide runtime task and resource management. As the processor count continues to increase, it is important to analyze the scalability of runtime managers at the system-level for different communication architectures. In this chapter, the authors analyze the scalability of an Application-Specific Instruction-Set Processor (ASIP) for runtime management called OSIP on two platform paradigms: shared and distributed memory. For the former, a generic bus is used as interconnect. For distributed memory, a Network-on-Chip (NoC) is used. The effects of OSIP and the communication architecture are jointly investigated from the system point of view, based on a broad case study with real applications (an H.264 video decoder and a digital receiver for wireless communications) and a synthetic benchmark application.