Comment by invertedohm

Kernel 4.18 is _ancient_, weird to test on that. Also I wonder if the whole performance increase can't just be achieved by lowering the readahead size a bit. I see in their notes they have a decent SSD but set the blockdev readahead to 64. Depending on your workload it's much more performant to lower that to 16. As mentioned in TFA, fast storage is the most important factor here, and in my experience combining that with a smaller readahead pretty much fixes any read amplification issues you get with the larger readahead.