new file mode 100755
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+#!/usr/bin/env python3
+#
+# Test to compare performance of write requests for two qemu-img binary files.
+#
+# The idea of the test comes from intention to check the benefit of c8bb23cbdbe
+# "qcow2: skip writing zero buffers to empty COW areas".
+#
+# Copyright (c) 2020 Virtuozzo International GmbH.
+#
+# 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/>.
+#
+
+
+import sys
+import os
+import subprocess
+import simplebench
+
+
+def bench_func(env, case):
+ """ Handle one "cell" of benchmarking table. """
+ return bench_write_req(env['qemu_img'], env['image_name'],
+ case['block_size'], case['block_offset'],
+ case['cluster_size'])
+
+
+def qemu_img_pipe(*args):
+ '''Run qemu-img and return its output'''
+ subp = subprocess.Popen(list(args),
+ stdout=subprocess.PIPE,
+ stderr=subprocess.STDOUT,
+ universal_newlines=True)
+ exitcode = subp.wait()
+ if exitcode < 0:
+ sys.stderr.write('qemu-img received signal %i: %s\n'
+ % (-exitcode, ' '.join(list(args))))
+ return subp.communicate()[0]
+
+
+def bench_write_req(qemu_img, image_name, block_size, block_offset,
+ cluster_size):
+ """Benchmark write requests
+
+ The function creates a QCOW2 image with the given path/name. Then it runs
+ the 'qemu-img bench' command and makes series of write requests on the
+ image clusters. Finally, it returns the total time of the write operations
+ on the disk.
+
+ qemu_img -- path to qemu_img executable file
+ image_name -- QCOW2 image name to create
+ block_size -- size of a block to write to clusters
+ block_offset -- offset of the block in clusters
+ cluster_size -- size of the image cluster
+
+ Returns {'seconds': int} on success and {'error': str} on failure.
+ Return value is compatible with simplebench lib.
+ """
+
+ if not os.path.isfile(qemu_img):
+ print(f'File not found: {qemu_img}')
+ sys.exit(1)
+
+ image_dir = os.path.dirname(os.path.abspath(image_name))
+ if not os.path.isdir(image_dir):
+ print(f'Path not found: {image_name}')
+ sys.exit(1)
+
+ image_size = 1024 * 1024 * 1024
+
+ args_create = [qemu_img, 'create', '-f', 'qcow2', '-o',
+ f'cluster_size={cluster_size}',
+ image_name, str(image_size)]
+
+ count = int(image_size / cluster_size) - 1
+ step = str(cluster_size)
+
+ args_bench = [qemu_img, 'bench', '-w', '-n', '-t', 'none', '-c',
+ str(count), '-s', f'{block_size}', '-o', str(block_offset),
+ '-S', step, '-f', 'qcow2', image_name]
+
+ try:
+ qemu_img_pipe(*args_create)
+ except OSError as e:
+ os.remove(image_name)
+ return {'error': 'qemu_img create failed: ' + str(e)}
+
+ try:
+ ret = qemu_img_pipe(*args_bench)
+ except OSError as e:
+ os.remove(image_name)
+ return {'error': 'qemu_img bench failed: ' + str(e)}
+
+ os.remove(image_name)
+
+ if 'seconds' in ret:
+ ret_list = ret.split()
+ index = ret_list.index('seconds.')
+ return {'seconds': float(ret_list[index-1])}
+ else:
+ return {'error': 'qemu_img bench failed: ' + ret}
+
+
+if __name__ == '__main__':
+
+ if len(sys.argv) < 4:
+ program = os.path.basename(sys.argv[0])
+ print(f'USAGE: {program} <path to qemu-img binary file> '
+ '<path to another qemu-img to compare performance with> '
+ '<full or relative name for QCOW2 image to create>')
+ exit(1)
+
+ # Test-cases are "rows" in benchmark resulting table, 'id' is a caption
+ # for the row, other fields are handled by bench_func.
+ test_cases = [
+ {
+ 'id': '<cluster front>',
+ 'block_size': 4096,
+ 'block_offset': 0,
+ 'cluster_size': 1048576
+ },
+ {
+ 'id': '<cluster middle>',
+ 'block_size': 4096,
+ 'block_offset': 524288,
+ 'cluster_size': 1048576
+ },
+ {
+ 'id': '<cross cluster>',
+ 'block_size': 1048576,
+ 'block_offset': 4096,
+ 'cluster_size': 1048576
+ },
+ {
+ 'id': '<cluster 64K>',
+ 'block_size': 4096,
+ 'block_offset': 0,
+ 'cluster_size': 65536
+ },
+ ]
+
+ # Test-envs are "columns" in benchmark resulting table, 'id is a caption
+ # for the column, other fields are handled by bench_func.
+ # Set the paths below to desired values
+ test_envs = [
+ {
+ 'id': '<qemu-img binary 1>',
+ 'qemu_img': f'{sys.argv[1]}',
+ 'image_name': f'{sys.argv[3]}'
+ },
+ {
+ 'id': '<qemu-img binary 2>',
+ 'qemu_img': f'{sys.argv[2]}',
+ 'image_name': f'{sys.argv[3]}'
+ },
+ ]
+
+ result = simplebench.bench(bench_func, test_envs, test_cases, count=3,
+ initial_run=False)
+ print(simplebench.ascii(result))
The script 'bench_write_req.py' allows comparing performances of write request for two qemu-img binary files. An example with (qemu-img binary 1) and without (qemu-img binary 2) the applied patch "qcow2: skip writing zero buffers to empty COW areas" (git commit ID: c8bb23cbdbe32f5) has the following results: SSD: ---------------- ------------------- ------------------- <qemu-img binary 1> <qemu-img binary 2> <cluster front> 0.10 +- 0.00 8.16 +- 0.65 <cluster middle> 0.10 +- 0.00 7.37 +- 1.10 <cross cluster> 7.40 +- 1.08 21.97 +- 4.19 <cluster 64K> 2.14 +- 0.94 8.48 +- 1.66 ---------------- ------------------- ------------------- HDD: ---------------- ------------------- ------------------- <qemu-img binary 1> <qemu-img binary 2> <cluster front> 2.30 +- 0.01 6.19 +- 0.06 <cluster middle> 2.20 +- 0.09 6.20 +- 0.06 <cross cluster> 8.32 +- 0.16 8.26 +- 0.14 <cluster 64K> 8.20 +- 0.05 6.26 +- 0.10 ---------------- ------------------- ------------------- Suggested-by: Denis V. Lunev <den@openvz.org> Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> --- v5: 01: 'cluster_size' made variable. 02: <simple case> deleted as duplicated. 03: A case with cluster size 64K was added. 04: The comments amended as Vladimir suggested. 05: Superfluous variables removed. 06: 'finally' block removed from function bench_write_req() 07: The names of test cases changed. 08: The 'block_size' of <cross cluster> set to the cluster size. scripts/simplebench/bench_write_req.py | 170 +++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) create mode 100755 scripts/simplebench/bench_write_req.py