We at Scylla tune the kernel, drives, stride, clock source automatically and benchmark the disk to figure out what's its maximum parallelism so it won't queue (we can saturate 8 NVMe) and we'll do the queuing within the DB's userspace so we can prioritize real time queries over background tasks:

https://www.scylladb.com/2018/04/19/scylla-i-o-scheduler-3/