This article talks about how AMD and NVIDIA have built their BVH-es (bounding volume hierarchy).

Raytracing aims to accurately model light by following the paths of light rays and seeing what they hit. However, raytracing is quite expensive compared to say, calculating light values by taking a pixel’s distance to light sources and doing an inverse square root. You need to send off a lot of rays to get enough rays to hit each pixel. On top of that, a ray could potentially hit any object in the scene. Obviously, you don’t want to do intersection tests against every piece of geometry. That’s where a bounding volume hierarchy (BVH) comes to implement a divide-and-conquer approach to seeing what a ray hits.