Re: [PATCH 0/1] Add swappiness argument to memory.reclaim

Shakeel Butt
2023-11-30T20:30:44Z

On Thu, Nov 30, 2023 at 11:47 AM Dan Schatzberg
<schatzberg.dan@gmail.com> wrote:
>
> On Thu, Nov 30, 2023 at 11:56:42AM -0500, Johannes Weiner wrote:
> > [...]
> > So I wouldn't say it's merely a reclaim hint. It controls a very
> > concrete and influential factor in VM decision making. And since the
> > global swappiness is long-established ABI, I don't expect its meaning
> > to change significantly any time soon.
>
> I want to add to this last point. While swappiness does not have
> terribly well-defined semantics - it is the (only?) existing mechanism
> to control balance between anon and file reclaim. I'm merely
> advocating for the ability to adjust swappiness during proactive
> reclaim separately from reactive reclaim. To what degree the behavior
> and semantics of swappiness change is a bit orthogonal here.

Let me ask my question in this chain as it might have been missed:

Whatever the semantics of swappiness are (including the edge cases
like no swap, file_is_tiny, trim cache), should the reclaim code treat
the global swappiness and user-provided swappiness differently?