[wyldfire]

A classic from [1]:

> An aircraft company discovered that it was cheaper to fly its planes with less fuel on board. The planes would be lighter and use less fuel and money was saved. On rare occasions however the amount of fuel was insufficient, and the plane would crash. This problem was solved by the engineers of the company by the development of a special OOF (out-of-fuel) mechanism. In emergency cases a passenger was selected and thrown out of the plane. (When necessary, the procedure was repeated.) A large body of theory was developed and many publications were devoted to the problem of properly selecting the victim to be ejected. Should the victim be chosen at random? Or should one choose the heaviest person? Or the oldest? Should passengers pay in order not to be ejected, so that the victim would be the poorest on board? And if for example the heaviest person was chosen, should there be a special exception in case that was the pilot? Should first class passengers be exempted? Now that the OOF mechanism existed, it would be activated every now and then, and eject passengers even when there was no fuel shortage. The engineers are still studying precisely how this malfunction is caused.

[1] https://lwn.net/Articles/104185/

[antisemiotic]

Fortunately, engineers have invented a way to attach a Strolling Wheelbarrow After Plane, where you can stash the sleeping passengers without ejecting them out of the plane entirely. This has the unpleasant side effect of slowing down the journey for everyone when passengers wake up inorderly (and God forbid everyone wake up at the same time), though.

[Annatar]

What I still do not understand is why people continue to turn a blind eye to this instead of switching to SmartOS. I just don't get it.

[nisa]

How does Solaris/SmartOS handles that situation?

[PeCaN]

It doesn't get in that situation, because malloc() can return null on Solaris (i.e. it never¹ overcommits).

While in general I think this is vastly better than the somewhat insane Linux OOM killer, you can get in awkward situations where you can't start any processes (including a root shell) because you're out of memory.

I rather like the FreeBSD solution to this, which is to not overcommit, but after a certain number of allocation failures it kills the process using the most memory. This prevents situations where you can't start any processes.

There's no one-size-fits-all solution to handling low memory conditions, but the Linux solution manages to almost never do what you want which is kind of impressive in a way.

¹ I seem to recall hearing somewhere that you can allow allocations to overcommit on a per-application basis on later versions of Solaris, but don't quote me on this.

[floatboth]

> FreeBSD solution to this, which is to not overcommit

Where did this myth come from? Did y'all just assume that the vm.overcommit sysctl actually makes sense and zero means "no overcommit"? :)

https://news.ycombinator.com/item?id=20623919

But indeed, OOM killer kills the largest process, which makes more sense in most scenarios than Linux's "badness" scoring.

[PeCaN]

Huh, I had no idea it worked like that. That's bizarre.