On Wed, Jan 05, 2022 at 11:09:57AM -0800, Darrick J. Wong wrote:
> On Thu, Jan 06, 2022 at 12:19:05AM +0800, Zorro Lang wrote:
> > On Mon, Jan 03, 2022 at 06:04:17PM -0800, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@xxxxxxxxxx>
> > >
> > > This test checks that speculative file preallocations are transferred to
> > > threads writing other files when space is low. Since we have background
> > > threads to clear those preallocations, it's possible that the test
> > > program might not get a speculative preallocation on the first try.
> > >
> > > This problem has become more pronounced since the introduction of
> > > background inode inactivation since userspace no longer has direct
> > > control over the timing of file blocks being released from unlinked
> > > files. As a result, the author has seen an increase in sporadic
> > > warnings from this test about speculative preallocations not appearing.
> > >
> > > Therefore, modify the function to try up to five times to create the
> > > speculative preallocation before emitting warnings that then cause
> > > golden output failures.
> > >
> > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> > > ---
> > > tests/xfs/014 | 41 +++++++++++++++++++++++++----------------
> > > 1 file changed, 25 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/tests/xfs/014 b/tests/xfs/014
> > > index a605b359..1f0ebac3 100755
> > > --- a/tests/xfs/014
> > > +++ b/tests/xfs/014
> > > @@ -33,27 +33,36 @@ _cleanup()
> > > # failure.
> > > _spec_prealloc_file()
> > > {
> > > - file=$1
> > > + local file=$1
> > > + local prealloc_size=0
> > > + local i=0
> > >
> > > - rm -f $file
> > > + # Now that we have background garbage collection processes that can be
> > > + # triggered by low space/quota conditions, it's possible that we won't
> > > + # succeed in creating a speculative preallocation on the first try.
> > > + for ((tries = 0; tries < 5 && prealloc_size == 0; tries++)); do
> > > + rm -f $file
> > >
> > > - # a few file extending open-write-close cycles should be enough to
> > > - # trigger the fs to retain preallocation. write 256k in 32k intervals to
> > > - # be sure
> > > - for i in $(seq 0 32768 262144); do
> > > - $XFS_IO_PROG -f -c "pwrite $i 32k" $file >> $seqres.full
> > > + # a few file extending open-write-close cycles should be enough
> > > + # to trigger the fs to retain preallocation. write 256k in 32k
> > > + # intervals to be sure
> > > + for i in $(seq 0 32768 262144); do
> > > + $XFS_IO_PROG -f -c "pwrite $i 32k" $file >> $seqres.full
> > > + done
> > > +
> > > + # write a 4k aligned amount of data to keep the calculations
> > > + # simple
> > > + $XFS_IO_PROG -c "pwrite 0 128m" $file >> $seqres.full
> > > +
> > > + size=`_get_filesize $file`
> > > + blocks=`stat -c "%b" $file`
> > > + blocksize=`stat -c "%B" $file`
> > > +
> > > + prealloc_size=$((blocks * blocksize - size))
> >
> > So we only try same pwrite operations 5 times, and only check the prealloc_size after 5
> > times done? Should we break from this loop once prealloc_size > 0?
>
> The second clause of the for loop tests for that, does it not?
Oh, yes, sorry I missed the "&& prealloc_size == 0", I thought you just gave it 5 tries :)
So this patch is good to me.
Reviewed-by: Zorro Lang <zlang@xxxxxxxxxx>
>
> --D
>
> >
> > Thanks,
> > Zorro
> >
> > > done
> > >
> > > - # write a 4k aligned amount of data to keep the calculations simple
> > > - $XFS_IO_PROG -c "pwrite 0 128m" $file >> $seqres.full
> > > -
> > > - size=`_get_filesize $file`
> > > - blocks=`stat -c "%b" $file`
> > > - blocksize=`stat -c "%B" $file`
> > > -
> > > - prealloc_size=$((blocks * blocksize - size))
> > > if [ $prealloc_size -eq 0 ]; then
> > > - echo "Warning: No speculative preallocation for $file." \
> > > + echo "Warning: No speculative preallocation for $file after $tries iterations." \
> > > "Check use of the allocsize= mount option."
> > > fi
> > >
> > >
> >
>
