Libfairydust is a small wrapper library intended for use with GPU clusters that 'hijacks' CUDA and OpenCL calls. It can be used to 're-route' calls to a certain GPU, so a process requesting GPU#0 might end up running on GPU#4 without knowing (or caring) about it. This works completely transparently and does not need any sort of 'cooperation' from the application, changes to code, or relinking.