While there have been several proposals of high performance global computing systems, scheduling schemes for the systems have not been well investigated. The reason is difficulties of evaluation by large-scale benchmarks with reproducible results. This paper describes an overview of the Bricks simulator that evaluates scheduling schemes on a typical high-performance global computing system. Bricks can simulate various behaviors of global computing systems, especially the behavior of networks and resource scheduling algorithms. Moreover, Bricks is componentalized such that not only its constituents could be replaced to simulate various different system algorithms, but also allows incorporation of existing global computing components via its foreign interface. To test the validity of the latter characteristics, we incorporated the NWS %(Network Weather Service) system, which monitors and forecasts global computing systems behavior. Experiments were conducted by running NWS under a real environment versus the simulated environment given the observed parameters of the real environment. Under both environments, NWS behaved similarly, making quite comparative forecasts.