A more recent GPU paper that deep-dives into NVidia Volta through microbenchmarks. This penetrates deeply into black-box magic, showing off and reverse-engineering NVidia's SASS assembly of the machine itself (below the PTX-assembly layer the typical CUDA programmer would be familiar with).

It is clear that the NVidia Volta GPU architecture includes memory barriers figured out by the PTX->SASS compiler, and I feel like I got a sense of what the instruction-scheduler of Volta (the chip itself) was doing.

Though this is an advanced read, it is one of the few online resources I'm aware of that goes into the nitty-gritty of how NVidia's popular GPUs actually work and execute code. Maybe not a "must read" for most GPU-programmers, but a useful read if you're trying to grab every ounce of performance from an NVidia GPU.