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Date: Sun, 17 Dec 2023 21:46:56 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Yu Zhao
 <yuzhao@google.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 Jesse Barnes <jsbarnes@google.com>, Suren Baghdasaryan <surenb@google.com>,
 Guru Anbalagane <gurua@google.com>, David Rientjes <rientjes@google.com>
Subject: Re: [GIT PULL] hotfixes for 6.7-rc6
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On Sun, 17 Dec 2023 15:40:19 +0000 Matthew Wilcox <willy@infradead.org> wrote:

> On Sat, Dec 16, 2023 at 04:16:45PM -0800, Linus Torvalds wrote:
> > On Fri, 15 Dec 2023 at 20:57, Yu Zhao <yuzhao@google.com> wrote:
> > >
> > > There has been a short-term plan, i.e., moving some of folio->flags to
> > > the lower bits of folio->lru so that we can drop the Kconfig
> > > constraint. I have discussed this with Willy but never acted on it. My
> > > priority has been to surface more of our ideas that can potentially
> > > save users money on memory to the community. I'm CC'ing our team
> > > leads. Please feel free to let us know your preference on the
> > > priority.
> > 
> > This is definitely a "eventually" thing on my wishlist, so I was more
> > just wanting to hear that there is a plan, and somebody working on
> > it..
> 
> "eventually" we should get rid of LRUs altogether.  They're no good for
> a modern CPU.
> 
> https://lore.kernel.org/linux-mm/ZTc7SHQ4RbPkD3eZ@casper.infradead.org/
> 

OK, but...

What of the cost of physical I/O?  If a computationally more expensive
scan results in less I/O (hopefully) then the balance is altered?