Re: mkfs.xfs "concurrency" change concerns

[Christoph Hellwig <hch@infradead.org>]

On Thu, Oct 09, 2025 at 03:13:47PM -0500, Eric Sandeen wrote:
> Hey all -
> 
> this got long, so tl;dr:
> 
> 1) concurrency geometry breaks some xfstests for me
> 2) concurrency behavior is not consistent w/ loopback vs. imagefile
> 3) concurrency defaults to the mkfs machine not the mount machine
> 
> In detail:
> 
> So, I realize I'm late to the game here and didn't review the patches
> before they went in, but it looks like the "concurrency" mkfs.xfs
> arguments and defaults are breaking several xfstests.
> 
> 4738ff0 mkfs: allow sizing realtime allocation groups for concurrency
> c02a1873 mkfs: allow sizing internal logs for concurrency
> 9338bc8b mkfs: allow sizing allocation groups for concurrency
> 
> Specifically, xfs/078, xfs/216, and xfs/217 are failing for us
> on various machines with between 8 and 128 CPUS, due to the
> fundamental change in geometry that results from the new
> concurrency behavior, which makes any consistent golden
> output that involves geometry details quite difficult.

Did anything ever come out of this?  We're hitting errors in exactly
those tests in the zoned XFS CI (which also tests regular XFS).
Shin'ichiro recently spent some time tracking these down, which
finally made me remember this thread.