Re: [GIT PULL] hotfixes for 6.7-rc6

[Andrew Morton]

On Sun, 17 Dec 2023 15:40:19 +0000 Matthew Wilcox <willy@xxxxxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx/
> 

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?