[profquail]

It sounds like the NCSU guys are using the CPU as a prefetcher to speed up GPU kernel execution, not using the GPU to speed up normal CPU programs as the ExtremeTech article implies.

The article says the same thing you are -- that the CPU is used as a prefetcher for the GPU; read the 3rd paragraph:

To achieve the 20% boost, the researchers reduce the CPU to a fetch/decode unit, and the GPU becomes the primary computation unit. This works out well because CPUs are generally very strong at fetching data from memory, and GPUs are essentially just monstrous floating point units. In practice, this means the CPU is focused on working out what data the GPU needs (pre-fetching), the GPU’s pipes stay full, and a 20% performance boost arises.