Altera Kernel Report Bandwidth Problem

Depending on the operating frequency of your kernel and external memory on your board, and also the number of external memory banks, you need to read or write a certain number of bytes per clock to be able to fully utilize the external memory bandwidth. What the profiler is trying to tell you is that you are not fully utilizing the external memory bandwidth since your accesses are too narrow. You can increase the bandwidth efficiency by unrolling the loop that is iterating over your external memory reads/writes. Note that you can also fully utilize the bandwidth if you have multiple narrow reads/writes but this will also result in a high amount of collision on the memory bus and lots of stalls in the pipeline.