Neither executables nor shared libraries are going to be evicted if they are in active use and have the "accessed" bit set in their page tables. This code has been present in the kernel mm/vmscan.c at least since 2012.

▲

shatsky 3 days ago | parent [-]

Will look into that again. If you're right about unevictability of these pages, what is the mechanism which causes sudden extreme degradation of performance when system is almost out of memory due to some app gradually consuming it, from quite responsive system to totally unresponsive system which can stay stuck with trashing disk for ages until oom will fire?

	▲	man8alexd 3 days ago \| parent [-]
		Once your active working set starts spilling into swap, the performance degradation goes exponential. The difference in latency between RAM and SSD is orders of magnitude. Assuming 10^3 difference, 0.1% memory excess causes 2x degradation, 1% - 10x degradation, 10% - 100x degradation.