Real-time operating systems lay claim to multitasking resource accessing control. Resources competition not only results in priority inversion and tasks blocking, but also prolongs timing delay caused by acquiring resources regularly. Although conventional resources accessing protocol works out priority inversion issues, there are still some defects such as frequent context switch, scheduling efficiency etc. With a research on the implement of MiniCore OS and SRP, this paper analyses the detailed criteria of scheduling and demonstrates the causation of low scheduling efficiency under SRP. To solve these issues above, we proposed and implemented a ready queue based on winner tree and a job selection mechanism with low timing overhead. Theoretical analyses and experiment results justify the better performance on large scale tasks scheduling under SRP protocol.