1#!/usr/bin/env python3
2#
3# Test to compare performance of write requests for two qemu-img binary files.
4#
5# The idea of the test comes from intention to check the benefit of c8bb23cbdbe
6# "qcow2: skip writing zero buffers to empty COW areas".
7#
8# Copyright (c) 2020 Virtuozzo International GmbH.
9#
10# This program is free software; you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation; either version 2 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the GNU General Public License
21# along with this program.  If not, see <http://www.gnu.org/licenses/>.
22#
23
24
25import sys
26import os
27import subprocess
28import simplebench
29from results_to_text import results_to_text
30
31
32def bench_func(env, case):
33    """ Handle one "cell" of benchmarking table. """
34    return bench_write_req(env['qemu_img'], env['image_name'],
35                           case['block_size'], case['block_offset'],
36                           case['cluster_size'])
37
38
39def qemu_img_pipe(*args):
40    '''Run qemu-img and return its output'''
41    subp = subprocess.Popen(list(args),
42                            stdout=subprocess.PIPE,
43                            stderr=subprocess.STDOUT,
44                            universal_newlines=True)
45    exitcode = subp.wait()
46    if exitcode < 0:
47        sys.stderr.write('qemu-img received signal %i: %s\n'
48                         % (-exitcode, ' '.join(list(args))))
49    return subp.communicate()[0]
50
51
52def bench_write_req(qemu_img, image_name, block_size, block_offset,
53                    cluster_size):
54    """Benchmark write requests
55
56    The function creates a QCOW2 image with the given path/name. Then it runs
57    the 'qemu-img bench' command and makes series of write requests on the
58    image clusters. Finally, it returns the total time of the write operations
59    on the disk.
60
61    qemu_img     -- path to qemu_img executable file
62    image_name   -- QCOW2 image name to create
63    block_size   -- size of a block to write to clusters
64    block_offset -- offset of the block in clusters
65    cluster_size -- size of the image cluster
66
67    Returns {'seconds': int} on success and {'error': str} on failure.
68    Return value is compatible with simplebench lib.
69    """
70
71    if not os.path.isfile(qemu_img):
72        print(f'File not found: {qemu_img}')
73        sys.exit(1)
74
75    image_dir = os.path.dirname(os.path.abspath(image_name))
76    if not os.path.isdir(image_dir):
77        print(f'Path not found: {image_name}')
78        sys.exit(1)
79
80    image_size = 1024 * 1024 * 1024
81
82    args_create = [qemu_img, 'create', '-f', 'qcow2', '-o',
83                   f'cluster_size={cluster_size}',
84                   image_name, str(image_size)]
85
86    count = int(image_size / cluster_size) - 1
87    step = str(cluster_size)
88
89    args_bench = [qemu_img, 'bench', '-w', '-n', '-t', 'none', '-c',
90                  str(count), '-s', f'{block_size}', '-o', str(block_offset),
91                  '-S', step, '-f', 'qcow2', image_name]
92
93    try:
94        qemu_img_pipe(*args_create)
95    except OSError as e:
96        os.remove(image_name)
97        return {'error': 'qemu_img create failed: ' + str(e)}
98
99    try:
100        ret = qemu_img_pipe(*args_bench)
101    except OSError as e:
102        os.remove(image_name)
103        return {'error': 'qemu_img bench failed: ' + str(e)}
104
105    os.remove(image_name)
106
107    if 'seconds' in ret:
108        ret_list = ret.split()
109        index = ret_list.index('seconds.')
110        return {'seconds': float(ret_list[index-1])}
111    else:
112        return {'error': 'qemu_img bench failed: ' + ret}
113
114
115if __name__ == '__main__':
116
117    if len(sys.argv) < 4:
118        program = os.path.basename(sys.argv[0])
119        print(f'USAGE: {program} <path to qemu-img binary file> '
120              '<path to another qemu-img to compare performance with> '
121              '<full or relative name for QCOW2 image to create>')
122        exit(1)
123
124    # Test-cases are "rows" in benchmark resulting table, 'id' is a caption
125    # for the row, other fields are handled by bench_func.
126    test_cases = [
127        {
128            'id': '<cluster front>',
129            'block_size': 4096,
130            'block_offset': 0,
131            'cluster_size': 1048576
132        },
133        {
134            'id': '<cluster middle>',
135            'block_size': 4096,
136            'block_offset': 524288,
137            'cluster_size': 1048576
138        },
139        {
140            'id': '<cross cluster>',
141            'block_size': 1048576,
142            'block_offset': 4096,
143            'cluster_size': 1048576
144        },
145        {
146            'id': '<cluster 64K>',
147            'block_size': 4096,
148            'block_offset': 0,
149            'cluster_size': 65536
150        },
151    ]
152
153    # Test-envs are "columns" in benchmark resulting table, 'id is a caption
154    # for the column, other fields are handled by bench_func.
155    # Set the paths below to desired values
156    test_envs = [
157        {
158            'id': '<qemu-img binary 1>',
159            'qemu_img': f'{sys.argv[1]}',
160            'image_name': f'{sys.argv[3]}'
161        },
162        {
163            'id': '<qemu-img binary 2>',
164            'qemu_img': f'{sys.argv[2]}',
165            'image_name': f'{sys.argv[3]}'
166        },
167    ]
168
169    result = simplebench.bench(bench_func, test_envs, test_cases, count=3,
170                               initial_run=False)
171    print(results_to_text(result))
172