[sltkr]

The counterargument to this is that the kernel can make decisions based on nonlocal information about the system.

If your database server is the only process in the system that is using significant memory, then sure, you might as well manage it yourself. But if there are multiple processes competing for memory, the kernel is better equipped to decide which processes' pages should be paged out or kept into memory.

[electricshampo1]

Generally for perf critical use cases you dedicate the machine to the database. This simplifies many things (avoiding having to reason about sharing, etc etc).

[munchler]

This makes me wonder whether there would be value in an OS that is also a DBMS (or vice versa). In other words, if the DBMS has total control over the hardware, perhaps performance can be maximized without too much additional complexity.

[matt_d]

One example is DBOS: A Database-oriented Operating System, https://dbos-project.github.io/ / https://github.com/DBOS-project (more details under "Publications").

[sedachv]

This is a bad idea from the 1960s: IBM TPF, MUMPS, Pick. As soon as the hardware changes it becomes slower and more complicated.

[yellowapple]

That was back when hardware was changing to a significant degree, though. Nowadays, there ain't really much that's new about hardware today v. hardware from 10 or 20 years ago - hence operating systems / filesystems being able to remain mostly stable instead of suffering from the exact same problem.