#!/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
from results_to_text import results_to_text
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(results_to_text(result))
