On 05/26, Christoph Hellwig wrote:

On Tue, May 26, 2026 at 03:31:08AM +0100, Matthew Wilcox wrote:

quoted

quoted

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And what are you trying to say us with that?

This means, high-order pages were used up by EROFS which sets large folio by
default. So, I wanted to say the concern was based on actual data which was what
Mattew asked.

This isn't that though.  What you actually need is to show that high order
allocations are _failing_.

Exactly.

quoted

If what you want is large folios readily available, then what you want
is large folios used _everywhere_ because then they're easy to get!

Yes.

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If there's small folios in use, you need to reclaim a lot of memory in
order to reassemble large folios (it's the birthday paradox, similar to
the hash collision problem).

Yeah.  Although it seems we have an issue with > order costly folios
at the moment, but we should fix this.

And f2fs really needs to up the game and support large folios fully
so that we can run that kind of analysis there as well, without this
all this is just piling hacks on top of other hacks.

Ok, I'll revisit the large folio support in f2fs, and try to revisit the
problem afterwards.

Thanks,

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