tests/perf: Test lseek influence on qcow2 block-status

Block layer may recursively check block_status in file child of qcow2,
if qcow2 driver returned DATA. There are several test cases to check
influence of lseek on block_status performance. To see real difference
run on tmpfs.

Tests originally created by Kevin, I just refactored and put them
together into one executable file with simple output.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/perf/block/qcow2/convert-blockstatus

@@ -0,0 +1,71 @@
+#!/bin/bash
+#
+# Test lseek influence on qcow2 block-status
+#
+# Block layer may recursively check block_status in file child of qcow2, if
+# qcow2 driver returned DATA. There are several test cases to check influence
+# of lseek on block_status performance. To see real difference run on tmpfs.
+#
+# Copyright (c) 2019 Virtuozzo International GmbH. All rights reserved.
+#
+# Tests originally written by Kevin Wolf
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+if [ "$#" -lt 1 ]; then
+    echo "Usage: $0 SOURCE_FILE"
+    exit 1
+fi
+
+ROOT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )/../../../.." >/dev/null 2>&1 && pwd )"
+QEMU_IMG="$ROOT_DIR/qemu-img"
+QEMU_IO="$ROOT_DIR/qemu-io"
+
+size=1G
+src="$1"
+
+# test-case plain
+
+(
+$QEMU_IMG create -f qcow2 "$src" $size
+for i in $(seq 16384 -1 0); do
+    echo "write $((i * 65536)) 64k"
+done | $QEMU_IO "$src"
+) > /dev/null
+
+echo -n "plain: "
+/usr/bin/time -f %e $QEMU_IMG convert -n "$src" null-co://
+
+# test-case forward
+
+(
+$QEMU_IMG create -f qcow2 "$src" $size
+for i in $(seq 0 2 16384); do
+    echo "write $((i * 65536)) 64k"
+done | $QEMU_IO "$src"
+for i in $(seq 1 2 16384); do
+    echo "write $((i * 65536)) 64k"
+done | $QEMU_IO "$src"
+) > /dev/null
+
+echo -n "forward: "
+/usr/bin/time -f %e $QEMU_IMG convert -n "$src" null-co://
+
+# test-case prealloc
+
+$QEMU_IMG create -f qcow2 -o preallocation=metadata "$src" $size > /dev/null
+
+echo -n "prealloc: "
+/usr/bin/time -f %e $QEMU_IMG convert -n "$src" null-co://