[PATCH 3/3] xfs/294: performance is unreasonably slow

From: Dave Chinner <david@fromorbit.com>
To: fstests@vger.kernel.org
Subject: [PATCH 3/3] xfs/294: performance is unreasonably slow
Date: Wed, 11 Jan 2023 09:49:06 +1100	[thread overview]
Message-ID: <20230110224906.1171483-4-david@fromorbit.com> (raw)
In-Reply-To: <20230110224906.1171483-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

This creates a bunch of files in a dir, then deletes 97% of them
attempting to leave 1 allocated inode per inode chunk so that they
aren't freed. Performance is badly limited by task creation and
destruction for each inode created. Fix this by using "echo -n >
file" rather than touch so that the shell creates the empty files
without needing to fork/exec a separate task for each creation.

This reduces runtime from 45s down to 15s.

Also add more debug with inode counts and internal superblock
counter information for determining why this test may ENOSPC on the
final creation loop.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 tests/xfs/294 | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/tests/xfs/294 b/tests/xfs/294
index d381e2c85..1ce0d1cc5 100755
--- a/tests/xfs/294
+++ b/tests/xfs/294
@@ -28,6 +28,13 @@ _require_test_program "punch-alternating"
 _require_xfs_io_command "falloc"
 _require_xfs_io_command "fpunch"
 
+dump_freespace()
+{
+	df $SCRATCH_MNT
+	df -i $SCRATCH_MNT
+	$XFS_IO_PROG -rc "statfs -c" $SCRATCH_MNT
+}
+
 # We want to mkfs with a very specific geometry
 MKFS_OPTIONS=""
 _scratch_mkfs "-d size=512m -n size=8192 -i size=1024" >> $seqres.full 2>&1 \
@@ -37,7 +44,7 @@ _scratch_mount
 # Make a ton of mostly-empty inode clusters so we can always
 # make more inodes
 mkdir $SCRATCH_MNT/tmp
-for I in `seq 1 10000`; do touch $SCRATCH_MNT/tmp/$I; done
+for I in `seq 1 10000`; do echo -n > $SCRATCH_MNT/tmp/$I; done
 
 # These mostly-empty clusters will live here:
 mkdir $SCRATCH_MNT/clusters
@@ -50,7 +57,7 @@ rm -rf $SCRATCH_MNT/tmp
 mkdir $SCRATCH_MNT/testdir
 # roughly 20 chars per file
 for I in `seq 1 100`; do
-	touch $SCRATCH_MNT/testdir/12345678901234567890$I;
+	echo -n > $SCRATCH_MNT/testdir/12345678901234567890$I;
 done
 
 # File to fragment:
@@ -63,7 +70,7 @@ space=$(stat -f -c '%f * %S * 95 / 100' $SCRATCH_MNT | $BC_PROG)
 $XFS_IO_PROG -f -c "falloc 0 $space" $SCRATCH_MNT/fillfile ||
 	_fail "Could not allocate space"
 
-df -h $SCRATCH_MNT >> $seqres.full 2>&1
+dump_freespace >> $seqres.full 2>&1
 
 # Fill remaining space; let this run to failure
 dd if=/dev/zero of=$SCRATCH_MNT/spacefile1 oflag=direct >> $seqres.full 2>&1
@@ -75,12 +82,16 @@ $here/src/punch-alternating $SCRATCH_MNT/fragfile >> $seqres.full 2>&1
 # (and then some for good measure)
 dd conv=fsync if=/dev/zero of=$SCRATCH_MNT/spacefile2 bs=1M count=64 >> $seqres.full 2>&1
 
+dump_freespace >> $seqres.full 2>&1
+
 # Now populate the directory so that it must allocate these
 # fragmented blocks
 for I in `seq 1 1400`; do
-	touch $SCRATCH_MNT/testdir/12345678901234567890$I;
+	echo -n > $SCRATCH_MNT/testdir/12345678901234567890$I;
 done
 
+dump_freespace >> $seqres.full 2>&1
+
 # Now traverse that ugly thing!
 find $SCRATCH_MNT/testdir | sort | _filter_scratch | md5sum
 
-- 
2.38.1

