tests/qemu-iotests/tests/stream-under-throttle

#!/usr/bin/env python3
# group: rw
#
# Test streaming with throttle nodes on top
#
# Copyright (C) 2022 Red Hat, Inc.
#
# 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 asyncio
import os
from typing import List
import iotests
from iotests import qemu_img_create, qemu_io


image_size = 256 * 1024 * 1024
base_img = os.path.join(iotests.test_dir, 'base.img')
top_img = os.path.join(iotests.test_dir, 'top.img')


class TcgVM(iotests.VM):
    '''
    Variant of iotests.VM that uses -accel tcg.  Simply using
    iotests.VM.add_args('-accel', 'tcg') is not sufficient, because that will
    put -accel qtest before -accel tcg, and -accel arguments are prioritized in
    the order they appear.
    '''
    @property
    def _base_args(self) -> List[str]:
        # Put -accel tcg first so it takes precedence
        return ['-accel', 'tcg'] + super()._base_args


class TestStreamWithThrottle(iotests.QMPTestCase):
    def setUp(self) -> None:
        '''
        Create a simple backing chain between two images, write something to
        the base image.  Attach them to the VM underneath two throttle nodes,
        one of which has actually no limits set, but the other does.  Then put
        a virtio-blk device on top.
        This test configuration has been taken from
        https://gitlab.com/qemu-project/qemu/-/issues/1215
        '''
        qemu_img_create('-f', iotests.imgfmt, base_img, str(image_size))
        qemu_img_create('-f', iotests.imgfmt, '-b', base_img, '-F',
                        iotests.imgfmt, top_img, str(image_size))

        # Write something to stream
        qemu_io(base_img, '-c', f'write 0 {image_size}')

        blockdev = {
            'driver': 'throttle',
            'node-name': 'throttled-node',
            'throttle-group': 'thrgr-limited',
            'file': {
                'driver': 'throttle',
                'throttle-group': 'thrgr-unlimited',
                'file': {
                    'driver': iotests.imgfmt,
                    'node-name': 'unthrottled-node',
                    'file': {
                        'driver': 'file',
                        'filename': top_img
                    }
                }
            }
        }

        # Issue 1215 is not reproducible in qtest mode, which is why we need to
        # create an -accel tcg VM
        self.vm = TcgVM()
        self.vm.add_object('iothread,id=iothr0')
        self.vm.add_object('throttle-group,id=thrgr-unlimited')
        self.vm.add_object('throttle-group,id=thrgr-limited,'
                           'x-iops-total=10000,x-bps-total=104857600')
        self.vm.add_blockdev(self.vm.qmp_to_opts(blockdev))
        self.vm.add_device('virtio-blk,iothread=iothr0,drive=throttled-node')
        if iotests.qemu_default_machine == 's390-ccw-virtio':
            self.vm.add_args('-no-shutdown')
        self.vm.launch()

    def tearDown(self) -> None:
        self.vm.shutdown()
        os.remove(top_img)
        os.remove(base_img)

    def test_stream(self) -> None:
        '''
        Do a simple stream beneath the two throttle nodes.  Should complete
        with no problems.
        '''
        self.vm.cmd('block-stream',
                    job_id='stream',
                    device='unthrottled-node')

        # Should succeed and not time out
        try:
            self.vm.run_job('stream')
        except asyncio.TimeoutError:
            # VM may be stuck, kill it before tearDown()
            self.vm.kill()
            raise


if __name__ == '__main__':
    # Must support backing images
    iotests.main(supported_fmts=['qcow', 'qcow2', 'qed'],
                 supported_protocols=['file'],
                 required_fmts=['throttle'])