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.