Multiprocessor Resource Sharing Protocol (MrsP) is a hard real-time multiprocessor resource sharing protocol for fully partitioned fixed-priority systems, and adopts a novel helping mechanism to allow task migrations during resource accessing. Previous research focusing on analysing MrsP systems have delivered two forms of timing analysis which effectively bound response time and migration cost of tasks under MrsP, and have demonstrated advantages of this protocol. An adjustable non-preemptive section is also introduced that effectively reduces the number of migrations needed during each resource access. However, these analysis methods are only applicable if a non-nested resource accessing model is assumed. In addition, there is no clear approach towards the configuration of the non-preemptive section length, and the computation cost for applying the analysis remains unknown. In this paper, we extend the MrsP analysis for systems with nested resources. Major run-time costs incurred by MrsP tasks are also taken into account to form a complete run-time cost-aware schedulability analysis. In addition, recommendations towards non-preemptive section configuration are given from both analytic and empiric perspectives. Finally, a set of evaluations are conducted to investigate schedulability of MrsP under nested resources and the cost for applying the proposed analysis. As a result of this paper, the schedulability test for MrsP is complete and the computation costs of its use are now understood.