[avar]

Even for those who understand this well, it's historically been really hard to coerce the Linux kernel into applying the right swap policies to your application.

As the author notes much of this has been improve by cgroups, and there's always been big hammers like mlock(), even with those things it can be hard to prevent memory thrashing in extreme cases. I've seen swap disabled completely by people who understood how it worked as a last result because of that.

It's always seemed to me that this was mainly a problem of the kernel configuration being too opaque. Why can't you configure on a system-wide basis that you can use swap e.g. only for anonymous pages and for nothing else?

Similarly it would be nice to have a facility for the OOMkiller to call out to userspace (it would need dedicated reserved memory for this) to ask a configured user program "what should I kill?". You might also want to do that when you have 10G left, not 0 bytes.

[Hello71]

Android has this last bit. as explained at https://www.youtube.com/watch?v=ikZ8_mRotT4&t=2145 (linked in the article) though, Linux does not have the facilities presently to determine when you have "10G left" in a way that applies across all system configurations.

[caf]

Swap is only used for anonymous pages (well, and dirty private file pages, which are basically the same thing).