Re: [PATCH 0/3] mm/lru_gen: move lru_gen control interface from debugfs to procfs

Liam R. Howlett
2025-11-28T16:14:49Z

* Matthew Wilcox <willy@infradead.org> [251128 10:16]:
> On Fri, Nov 28, 2025 at 10:53:12AM +0800, Zicheng Wang wrote:
> > Case study:
> > A widely observed issue on Android is that after application launch,

What do you mean by application launch? What does this mean in the
kernel context?

> > the oldest anon generation often becomes empty, and file pages
> > are over-reclaimed.
>
> You should fix the bug, not move the debug interface to procfs. NACK.

Barry recently sent an RFC [1] to affect LRU in the exit path for
Android. This was proven incorrect by Johannes, iirc, in another thread
I cannot find (destroys performance of calling the same command).

These ideas seem both related as it points to a suboptimal LRU in the
Android ecosystem, at least. It seems to stem from Androids life
(cycle) choices :)

I strongly agree with Willy. We don't want another userspace daemon
and/or interface, but this time to play with the LRU to avoid trying to
define and fix the problem.

Do you know if this affects others or why it is android specific?

[1]. https://lore.kernel.org/all/20250514070820.51793-1-21cnbao@gmail.com/