For HDD, it also needs to be tuned. In its default configuration, MGLRU 'just' manages multiple generations of working sets, but there's a min_ttl_ms tunable which tries hard to prevent file cache from being reclaimed, which is not enabled by default.

https://docs.kernel.org/admin-guide/mm/multigen_lru.html#thr...

You'd want to set it to 300 or 500, or even 1000 for the HDDs. Around 100-200 for SSDs/EMMCs helps as well.

And for anonymous pages swapping, you'd want to do that on zram (compressed swap in RAM). It also make wonders. You don't want to touch the (old) disk for that.

Here's my old article (before MGLRU): https://notes.valdikss.org.ru/linux-for-old-pc-from-2007/en/