Hey Skippy, don't get any water or coffee on the helm controls, or it might either not respond or go full ahead/reverse.
^-- Just one class of examples of what could wrong with not having physical controls.
Also, it takes a smaller explosive to crack/damage a touchscreen than physical controls into uncontrollability... and now you have a billion dollar paperweight.
There's several situations that need to be addressed in every VMM:
Cold pages - not being used
Warm/normal pages - average use pages
Hot pages - being used a lot
1. LRU/histogramming cold RO-code/RO-data pages to be paged out (dropped) or compressed when other pages are hotter and there's memory pressure.
2. Compressing or paging out to disk volatile RW-data when cold and other pages are hotter and there's memory pressure.
3. Pinning in memory (compressed and/or uncompressed) pages that are hot for performance reasons, unlocking them when they become less hot or others become hotter.
4. Having the ability (like on macOS) to signal applications that the system is under severe memory pressure (say "SIGMEM", "SIGLOWMEM" or "SIGOOM"), and to drop volatile data that can regenerated or is ephemeral.
Linux resource scheduling and prioritization and is pretty awful compared to its popularity.
TBH, there are very few OSes that get high-pressure resource scheduling and prioritization right under nearly all normal circumstances.
The hackaround for decades on Linux is always adding a tiny swap device, say 64-256 MiB on a fast device in order to 0) detect average high memory pressure with monitoring tools 1) prevent oddities under load without swap (as in OP example).
^-- Just one class of examples of what could wrong with not having physical controls.
Also, it takes a smaller explosive to crack/damage a touchscreen than physical controls into uncontrollability... and now you have a billion dollar paperweight.