Re: [PATCH v3 0/3] Implement numa node notifier

[Andrew Morton]

On Fri,  2 May 2025 10:36:21 +0200 Oscar Salvador <osalvador@xxxxxxx> wrote:

> Memory notifier is a tool that allow consumers to get notified whenever
> memory gets onlined or offlined in the system.
> Currently, there are 10 consumers of that, but 5 out of those 10 consumers
> are only interested in getting notifications when a numa node changes its
> memory state.
> That means going from memoryless to memory-aware of vice versa.
> 
> Which means that for every {online,offline}_pages operation they get
> notified even though the numa node might not have changed its state.

Why is this a problem?  Is there some bug?  Are these notifications so
frequent that there are significant inefficiencies here?

Further down-thread, Gregory tells us that Dan's patch "seems to fix
the underlying problem", but nobody (including Dan) told us about any
"problem" at all.