Re: [PATCH v5] mm/mempolicy: Weighted Interleave Auto-tuning

[Joshua Hahn <joshua.hahnjy@gmail.com>]

On Tue, 11 Feb 2025 16:17:52 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:

> On Fri,  7 Feb 2025 21:06:04 -0800 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:
> 
> > On Fri, 7 Feb 2025 18:20:09 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
> > 
> > > On Fri,  7 Feb 2025 12:13:35 -0800 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:
> > > 
> > > > This patch introduces an auto-configuration mode for the interleave
> > > > weights that aims to balance the two goals of setting node weights to be
> > > > proportional to their bandwidths and keeping the weight values low.
> > > > In order to perform the weight re-scaling, we use an internal
> > > > "weightiness" value (fixed to 32) that defines interleave aggression.
> > > 
> > > Question please.  How does one determine whether a particular
> > > configuration is working well?  To determine whether
> > > manual-configuration-A is better than manual-configuration-B is better
> > > than auto-configuration?
> > > 
> > > Leading to... how do we know that this patch makes the kernel better?
> > 
> > Hello Andrew,
> > 
> > Thank you for your interest in this patch!
> > 
> > To answer your 1st question: I think that users can do some
> >
> > ...
> >
> 
> Interesting, thanks.
> 
> Have we adequately documented all these considerations for our users or
> can we add some additional words in an appropriate place?

Hello Andrew,

I have documented these thoughs on a private document, but I think that
it will be beneficial for weighted interleave users to have this
knowledge to reference in the future as well.

I can think of two places where this information will benefit users the
most: I can elaborate further the motivations & decisions Gregory
and I made for this patch within the patch commit message, and also
in the ABI documentation. As Oscar suggested, appropriate details in
the code should hopefully make the decisions clearer for future
maintainers and developers as well.

Thank you again for your insight! I will have a v6 drafted up, and
I think it makes sense to pull this patch out of mm-unstable for now.
Have a great day!

Joshua