Re: [PATCH v8 0/5] block: add larger order folio instead of pages

[Christoph Hellwig <hch@lst.de>]

On Thu, Aug 08, 2024 at 04:04:03PM -0700, Luis Chamberlain wrote:
> This is not just about mTHP uses though, this can also affect buffered IO and
> direct IO patterns as well and this needs to be considered and tested as well.

Not sure what the above is supposed to mean.  Besides small tweaks
to very low-level helpers the changes are entirely in the direct I/O
path, and they optimize that path for folios larger than PAGE_SIZE.

> I've given this a spin on top of of the LBS patches [0] and used the LBS
> patches as a baseline. The good news is I see a considerable amount of
> larger IOs for buffered IO and direct IO, however for buffered IO there
> is an increase on unalignenment to the target filesystem block size and
> that can affect performance.

Compared to what?  There is nothing in the series here changing buffered
I/O patterns.  What do you compare?  If this series changes buffered
I/O patterns that is very well hidden and accidental, so we need to
bisect which patch does it and figure out why, but it would surprise me
a lot.