scripts/simplebench/bench_write_req.py

   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
  25 import sys
  26 import os
  27 import subprocess
  28 import simplebench
  29 from results_to_text import results_to_text
  30
  31
  32 def 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
  39 def 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
  52 def 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
 115 if __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))