linux-kernel - Re: [PATCH v2 00/13] forcealign for xfs

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Message-ID: <20240706075353.GA15212@lst.de>
Date: Sat, 6 Jul 2024 09:53:53 +0200
From: Christoph Hellwig <hch@....de>
To: John Garry <john.g.garry@...cle.com>
Cc: chandan.babu@...cle.com, djwong@...nel.org, dchinner@...hat.com,
	hch@....de, viro@...iv.linux.org.uk, brauner@...nel.org,
	jack@...e.cz, linux-xfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	catherine.hoang@...cle.com, martin.petersen@...cle.com
Subject: Re: [PATCH v2 00/13] forcealign for xfs

On Fri, Jul 05, 2024 at 04:24:37PM +0000, John Garry wrote:
> The actual forcealign patches are the same in this series, modulo an
> attempt for a fix in xfs_bunmapi_align().
> 
> Why forcealign?
> In some scenarios to may be required to guarantee extent alignment and
> granularity.
> 
> For example, for atomic writes, the maximum atomic write unit size would
> be limited at the extent alignment and granularity, guaranteeing that an
> atomic write would not span data present in multiple extents.
> 
> forcealign may be useful as a performance tuning optimization in other
> scenarios.

>From previous side discussion I know Dave disagrees, but given how
much pain the larger than FSB rtextents have caused I'm very skeptical
if taking this on is the right tradeoff.