A time warp implementation of Sharks World

The authors discuss the TWOS (Time Warp Operating System) implementations of the Shark´s World simulation, a simple simulation of sharks and fish swimming through a toroidal world. Shark´s World was coded and debugged in two man-weeks; after the initial debugging and tuning, it ran all tests without modifications. Shark´s World provides a good performance under TWOS. It has demonstrated speedups as high as 29.5, with efficiencies as high as 63.75%. With a sufficient number of sectors, TWOS provides a smooth speedup curve. If the number of sectors is close to the number of nodes, the speedup curve is likely to have a plateau between the points of two objects per node and one object per node. Shark´s World provides a test example for lazy cancellation versus aggressive cancellation. Due to its nature, lazy cancellation should do very well with Shark´s World, and does indeed do better than aggressive cancellation. The authors examine methods of improving TWOS performance on this application, and the possible effects of adding more complexity to the simulation