Take a look at this https://dl.acm.org/doi/pdf/10.1145/3341301.3359640 ; shows how newer kernels are slower. I have seen supercomputers like `summit` use linux 2.xx .

There are two performance problems presented here. One is the fact that the OS waits till a static memory bank water-level before triggering a cleanup.

The second is the one you pointed out; here again one thing to consider is cassandra's compression chunk size `chunk_length_in_kb`. readahead value less than chunk size makes cassandra slow in general. take a look at this https://thelastpickle.com/blog/2018/08/08/compression_perfor... for more info on it.