If a program is structured in a particular way to run through large spans of contiguous memory but only do trivial operations, then memory bandwidth can be maxe

If a program is structured in a particular way to run through large spans of contiguous memory but only do trivial operations, then memory bandwidth can be maxed out by the prefetcher and the cache wouldn't be used. Things like adding two huge images with SIMD and writing out a new image could be like this. It would be much better of course if the image is tiled and more operations are done per tile, which would use the cache. Good use of the prefetcher but poor use of the cache could still run through memory bandwdith.