# Performance Analysis of a 3D Wireless Massively Parallel Computer
## 4 Conclusions and Future Work  
Two topologies for a wireless interconnect network for a massively parallel computer (called A Ball Computer or the 'ABC') are presented in this paper. Considering the developments in wireless technologies during the past decade, they are close to meeting the criteria for such an application. However, this paper has shown that more improvements in transfer rate and, more importantly, in energy consumption are needed to be able to build a competitive real-world prototype of the ABC. We have reviewed several works on mm-wave on-chip radio and showed that an energy consumption of 0.05 pJ/bit/cm has already been achieved, which means that a 20 Gb/s transceiver of  
Figure 16: Link busy time when comm/comp ratio varies between 0.1 and 100,000 in a 5D grid with two sizes: 1000 nodes (**a**,**b**,**c**) and 2000 nodes (**d**,**e**,**f**) running FFTTM. Data sizes are 100 KB (**a**,**d**), 1 MB (**b**,**e**) and 10 MB (**c**,**f**). Figure 15: Link busy time when comm/comp ratio varies between 0.1 and 100,000 in ABC with two sizes: 1000 nodes (**a**,**b**,**c**) and 2000 nodes (**d**,**e**,**f**) running FFTTM. Data sizes are 100 KB (**a**,**d**), 1 MB (**b**,**e**) and 10 MB (**c**,**f**). this type will have an approximate power consumption of 1 mW. These are promising numbers and the emergence of terahertz on-chip radio devices in the future will mean a further improvement in both data rates and power demands. A 3D topology for the ABC concept is modelled in a simulation environment to perform experiments on the behaviour of the proposed platform under different situations. This paper has presented the performance analysis of the ABC based on processor and link utilisations. The link measurements are repeated with a simulated traditional 5D direct network (like IBM's Blue Gene topology) to have a basis for comparison. The packet-switching algorithm used in the simulation has been under scrutiny using the simulation results. The results have shown that for a given range of network parameters the performance of the ABC is comparable to (or sometimes even better than) a 5D network. The store-and-forward packet-switching algorithm used in the simulations is believed to contribute to the drop in performance in both the ABC and 5D topologies. Choosing a cut-through or especially a wormhole algorithm can improve the link efficiency. The link and processor performance are slightly reduced when the size of the network is increased from 1000 nodes to 2000, which implies that the FFT task model used in the simulations needs to be changed to let it use the full potential of a larger network. The experiments have also shown that switching to very high transfer rates does not always lead to a meaningful improvement in the performance. In most cases the processor utility does not increase much, but levels out or even drops when switching from 100 Gb/s to 1 Tb/s. In addition, the link busy time is sometimes unchanged after switching to 1 Tb/s. This suggests that, at least with the current packet-switching mechanism and task model, there is no need to consider data rates over 100 Gb/s. In case of using another switching algorithm or task model, this assumption may not be valid anymore. One of the paths for future work is to abandon the principle of having static nodes and let them have freedom of movement (at least to some extent). The self-autonomy given to the nodes turns them into an agent or robot rather than just processing nodes. This touches on the idea of swarm robotics /swarm computing. The wide range of possibilities in this path is very convincing. Agents (formerly referred to as nodes) can organise themselves to fit a given task. They can collaborate and coordinate based on the assigned task and even the geography and geometry they operate in. This also touches on areas like distributed control. The applications of such a system range from modelling biological systems to social systems, robust control systems, monitoring, rescue missions, urban life management and many more.