Re: mkfs.xfs "concurrency" change concerns

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Jun 15, 2026 at 07:19:22AM -0700, Christoph Hellwig wrote:
> 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.

Lukas Herbolt posted some fixes for a few of the fstests to inject
concurrency=0 into mkfs.  IIRC there weren't any changes for 078, but
you might ask him if he has more bugs to address.

--D