Search for huge pages in the documentation of a DBMS that implements its own caching in shared memory: Oracle [1], PostgreSQL [2], MySQL [3], etc. When you're caching hundreds of gigabytes, it makes a difference. Here's a benchmark comparing PostgreSQL performance with regular, large, and huge pages [4].
There was a really bad performance regression in Linux a couple of years ago that killed performance with large memory regions like this (can't find a useful link at the moment), and the short-term mitigation was to increase the huge page size from 2MB to 1GB.