linux-kernel - Re: [PATCH v3 0/4] allow partial folio write with iomap_folio

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Message-ID: <aK20jalLkbKedAz8@infradead.org>
Date: Tue, 26 Aug 2025 06:20:13 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Jinliang Zheng <alexjlzheng@...il.com>
Cc: hch@...radead.org, alexjlzheng@...cent.com, brauner@...nel.org,
	djwong@...nel.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-xfs@...r.kernel.org,
	yi.zhang@...wei.com
Subject: Re: [PATCH v3 0/4] allow partial folio write with iomap_folio_state

On Mon, Aug 25, 2025 at 07:39:21PM +0800, Jinliang Zheng wrote:
> Actually, I discovered this while reading (and studying) the code for large
> folios.
> 
> Given that short-writes are inherently unusual, I don't think this patchset
> will significantly improve performance in hot paths. It might help in scenarios
> with frequent memory hardware errors, but unfortunately, I haven't built a
> test scenario like that.
> 
> I'm posting this patchset just because I think we can do better in exception
> handling: if we can reduce unnecessary copying, why not?

I'm always interested in the motivation, especially for something
adding more code or doing large changes.  If it actually improves
performance it's much easier to argue for.  If it doesn't that doesn't
mean the patch is bad, but it needs to have other upsides.  I'll take
another close look, but please also add your motivation to the cover
letter and commit log for the next round.