Re: [PATCH 2/2] xfs/216: disable all concurrency scaling

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

On Thu, Jun 25, 2026 at 03:22:51PM +0200, Christoph Hellwig wrote:
> On Wed, Jun 24, 2026 at 10:44:04AM -0700, Darrick J. Wong wrote:
> > On Fri, Jun 19, 2026 at 07:09:29AM +0200, Christoph Hellwig wrote:
> > > This test currently disables log concurrency scaling, but even the
> > > data device concurrency scaling can create mismatching output on
> > > systems with a large CPU count.
> > > 
> > > Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> > > ---
> > >  tests/xfs/216 | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/tests/xfs/216 b/tests/xfs/216
> > > index 1749647c11f7..ce8bb528410b 100755
> > > --- a/tests/xfs/216
> > > +++ b/tests/xfs/216
> > > @@ -23,7 +23,7 @@ _cleanup()
> > >  _require_scratch
> > >  _scratch_mkfs_xfs >/dev/null 2>&1
> > >  if _scratch_mkfs_xfs_supports_concurrency -l >> $seqres.full 2>&1; then
> > > -	loop_mkfs_opts="-l concurrency=0"
> > > +	loop_mkfs_opts="-d concurrency=0 -l concurrency=0 -r concurrency=0"
> > 
> > /me notes that -lconcurrency is not compatible with -llogdev and the
> > loopdev is not formatted with SCRATCH_MKFS_OPTIONS, so this won't work
> > to disable the concurrency= mkfs options if fstests is being run with
> > SCRATCH_LOGDEV set.
> 
> Arrg.  I hate our option parsing mess.  Any good idea how we'd get
> the desired result?  Unless there's something easy I'd be tempted to
> leave it to the first person using an external log device and large
> cpu counts..

Yeah, that's me. :)

I just sent my latest batch of random fixes:
https://lore.kernel.org/fstests/178240619625.1665857.3954516357764795627.stgit@frogsfrogsfrogs/

I don't know that it's necessary to add -dconcurrency=0 for xfs/216
after that (it seemed to work for me) but I don't have any objections to
adding more:

if _mkfs_xfs_supported $loop_mkfs_opts -l concurrency=0 $loop_dev &>> $seqres.full; then
	loop_mkfs_opts="$loop_mkfs_opts -l concurrency=0"
fi
if _mkfs_xfs_supported $loop_mkfs_opts -d concurrency=0 $loop_dev &>> $seqres.full; then
	loop_mkfs_opts="$loop_mkfs_opts -d concurrency=0"
fi

--D