We have collected 10 personal computers; one is called the master and the other 9 are called slaves, because they do the actual work. The problem is one of modelling Brisbane's traffic. This type of simulation is useful because it allows traffic engineers to optimise road design and experiment with different control parameters. The movement of cars is simulated, as well as the behaviour of traffic lights and uncontrolled intersections. In order to simulate all of Brisbane's traffic at the individual car level, it would be normally be necessary to use a very fast computer system. Parallel computers offer a viable alternative to using one single very fast machine and make it possible to simulate very large systems.
Each computer models only a certain part of the map. Each time the screens are updated, the cars can be seen to move along roads. Each computer must talk to its neighbours to find out when a car must be transferred from one simulation to another. Thus, they must co-operate to solve the problem . By using 9 computers as slaves we are able to solve this problem 9 times faster than if we were only using one computer.
The PCs make use of the LINUX operating system and the parallel code uses standard tools like X and PVM.
The demonstration represents an accurate scaled model of a real parallel super
computer like the IBM SP2. The SP2 has processors which are orders of magnitude
faster than the PCs in this display, and uses a special high speed switch for
interprocessor communication. The QPSF system currently has 22
processors, but machines as large as 512 processors have been built.