Re: [f2fs-dev] Plans for F2FS Supporting Large Folios

[Jaegeuk Kim via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

Hi Ryan,

On 10/02, Ryan Roberts wrote:
> Hi Jaegeuk Kim, Chao Yu,
> 
> I heard (via Matthew Wilcox) that you may be in the process of forming plans to
> add large folio support to f2fs? If so, I wonder if you could let me know how
> those plans are progressing? I saw your v6.12-rc1 pull request did a lot of
> conversion from struct page to struct folio (of the small variety for now) but
> wondered if this is intended as pre-work for enabling large folios?
> 
> I've been doing a lot of work on the anonymous memory side to support large
> folios ("mTHP") and hook that up to arm64's contpte pgtable support. This
> improves performance nicely.
> 
> Additionally I have experimented (on XFS) with ensuring that text mappings are
> contpte mapped where possible and this reduces pressure in the iTLB to improve
> performance further. But it all relies on the file system supporting large
> folios. I'd very much like to realize these performance gains on Android, but
> that requires the file systems that Android uses to support large folios.
> 
> It would be great to understand your plans, if any, and figure out if/where Arm
> may be able to help accelerate activities in this area. I'm not (yet!) an fs
> expert, but I see that f2fs is already using iomap, so perhaps now that you are
> supporting small folios, switching up to large folios is not too big of a step?

Thanks for sharing the background. By any chance, have you talked larg folio
with Android kernel team? If indeed there's a fair benefit from Android side,
I'd like to circle back supporting it in f2fs seriously.

> 
> Thanks,
> Ryan


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