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xemu/tests/qemu-iotests/093
Alberto Garcia ef7a6a3c2a qemu-iotests: Test removing a throttle group member with a pending timer 
A throttle group can have several members, and each one of them can
have several pending requests in the queue.

The requests are processed in a round-robin fashion, so the algorithm
decides the drive that is going to run the next request and sets a
timer in it. Once the timer fires and the throttled request is run
then the next drive from the group is selected and a new timer is set.

If the user tried to remove a drive from a group and that drive had a
timer set then the code was not taking care of setting up a new timer
in one of the remaining members of the group, freezing their I/O.

This problem was fixed in 6fccbb475b,
and this patch adds a new test case that reproduces this exact
scenario.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-08-15 12:50:39 +02:00

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#!/usr/bin/env python
#
# Tests for IO throttling
#
# Copyright (C) 2015 Red Hat, Inc.
# Copyright (C) 2015-2016 Igalia, S.L.
#
# 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 iotests
nsec_per_sec = 1000000000
class ThrottleTestCase(iotests.QMPTestCase):
test_img = "null-aio://"
max_drives = 3
def blockstats(self, device):
result = self.vm.qmp("query-blockstats")
for r in result['return']:
if r['device'] == device:
stat = r['stats']
return stat['rd_bytes'], stat['rd_operations'], stat['wr_bytes'], stat['wr_operations']
raise Exception("Device not found for blockstats: %s" % device)
def setUp(self):
self.vm = iotests.VM()
for i in range(0, self.max_drives):
self.vm.add_drive(self.test_img)
self.vm.launch()
def tearDown(self):
self.vm.shutdown()
def configure_throttle(self, ndrives, params):
params['group'] = 'test'
# Set the I/O throttling parameters to all drives
for i in range(0, ndrives):
params['device'] = 'drive%d' % i
result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **params)
self.assert_qmp(result, 'return', {})
def do_test_throttle(self, ndrives, seconds, params, first_drive = 0):
def check_limit(limit, num):
# IO throttling algorithm is discrete, allow 10% error so the test
# is more robust
return limit == 0 or \
(num < seconds * limit * 1.1 / ndrives
and num > seconds * limit * 0.9 / ndrives)
# Set vm clock to a known value
ns = seconds * nsec_per_sec
self.vm.qtest("clock_step %d" % ns)
# Submit enough requests so the throttling mechanism kicks
# in. The throttled requests won't be executed until we
# advance the virtual clock.
rq_size = 512
rd_nr = max(params['bps'] / rq_size / 2,
params['bps_rd'] / rq_size,
params['iops'] / 2,
params['iops_rd'])
rd_nr *= seconds * 2
rd_nr /= ndrives
wr_nr = max(params['bps'] / rq_size / 2,
params['bps_wr'] / rq_size,
params['iops'] / 2,
params['iops_wr'])
wr_nr *= seconds * 2
wr_nr /= ndrives
# Send I/O requests to all drives
for i in range(rd_nr):
for drive in range(0, ndrives):
idx = first_drive + drive
self.vm.hmp_qemu_io("drive%d" % idx, "aio_read %d %d" %
(i * rq_size, rq_size))
for i in range(wr_nr):
for drive in range(0, ndrives):
idx = first_drive + drive
self.vm.hmp_qemu_io("drive%d" % idx, "aio_write %d %d" %
(i * rq_size, rq_size))
# We'll store the I/O stats for each drive in these arrays
start_rd_bytes = [0] * ndrives
start_rd_iops = [0] * ndrives
start_wr_bytes = [0] * ndrives
start_wr_iops = [0] * ndrives
end_rd_bytes = [0] * ndrives
end_rd_iops = [0] * ndrives
end_wr_bytes = [0] * ndrives
end_wr_iops = [0] * ndrives
# Read the stats before advancing the clock
for i in range(0, ndrives):
idx = first_drive + i
start_rd_bytes[i], start_rd_iops[i], start_wr_bytes[i], \
start_wr_iops[i] = self.blockstats('drive%d' % idx)
self.vm.qtest("clock_step %d" % ns)
# Read the stats after advancing the clock
for i in range(0, ndrives):
idx = first_drive + i
end_rd_bytes[i], end_rd_iops[i], end_wr_bytes[i], \
end_wr_iops[i] = self.blockstats('drive%d' % idx)
# Check that the I/O is within the limits and evenly distributed
for i in range(0, ndrives):
rd_bytes = end_rd_bytes[i] - start_rd_bytes[i]
rd_iops = end_rd_iops[i] - start_rd_iops[i]
wr_bytes = end_wr_bytes[i] - start_wr_bytes[i]
wr_iops = end_wr_iops[i] - start_wr_iops[i]
self.assertTrue(check_limit(params['bps'], rd_bytes + wr_bytes))
self.assertTrue(check_limit(params['bps_rd'], rd_bytes))
self.assertTrue(check_limit(params['bps_wr'], wr_bytes))
self.assertTrue(check_limit(params['iops'], rd_iops + wr_iops))
self.assertTrue(check_limit(params['iops_rd'], rd_iops))
self.assertTrue(check_limit(params['iops_wr'], wr_iops))
# Allow remaining requests to finish. We submitted twice as many to
# ensure the throttle limit is reached.
self.vm.qtest("clock_step %d" % ns)
# Connect N drives to a VM and test I/O in all of them
def test_all(self):
params = {"bps": 4096,
"bps_rd": 4096,
"bps_wr": 4096,
"iops": 10,
"iops_rd": 10,
"iops_wr": 10,
}
# Repeat the test with different numbers of drives
for ndrives in range(1, self.max_drives + 1):
# Pick each out of all possible params and test
for tk in params:
limits = dict([(k, 0) for k in params])
limits[tk] = params[tk] * ndrives
self.configure_throttle(ndrives, limits)
self.do_test_throttle(ndrives, 5, limits)
# Connect N drives to a VM and test I/O in just one of them a time
def test_one(self):
params = {"bps": 4096,
"bps_rd": 4096,
"bps_wr": 4096,
"iops": 10,
"iops_rd": 10,
"iops_wr": 10,
}
# Repeat the test for each one of the drives
for drive in range(0, self.max_drives):
# Pick each out of all possible params and test
for tk in params:
limits = dict([(k, 0) for k in params])
limits[tk] = params[tk] * self.max_drives
self.configure_throttle(self.max_drives, limits)
self.do_test_throttle(1, 5, limits, drive)
def test_burst(self):
params = {"bps": 4096,
"bps_rd": 4096,
"bps_wr": 4096,
"iops": 10,
"iops_rd": 10,
"iops_wr": 10,
}
ndrives = 1
# Pick each out of all possible params and test
for tk in params:
rate = params[tk] * ndrives
burst_rate = rate * 7
burst_length = 4
# Configure the throttling settings
settings = dict([(k, 0) for k in params])
settings[tk] = rate
settings['%s_max' % tk] = burst_rate
settings['%s_max_length' % tk] = burst_length
self.configure_throttle(ndrives, settings)
# Wait for the bucket to empty so we can do bursts
wait_ns = nsec_per_sec * burst_length * burst_rate / rate
self.vm.qtest("clock_step %d" % wait_ns)
# Test I/O at the max burst rate
limits = dict([(k, 0) for k in params])
limits[tk] = burst_rate
self.do_test_throttle(ndrives, burst_length, limits)
# Now test I/O at the normal rate
limits[tk] = rate
self.do_test_throttle(ndrives, 5, limits)
# Test that removing a drive from a throttle group should not
# affect the remaining members of the group.
# https://bugzilla.redhat.com/show_bug.cgi?id=1535914
def test_remove_group_member(self):
# Create a throttle group with two drives
# and set a 4 KB/s read limit.
params = {"bps": 0,
"bps_rd": 4096,
"bps_wr": 0,
"iops": 0,
"iops_rd": 0,
"iops_wr": 0 }
self.configure_throttle(2, params)
# Read 4KB from drive0. This is performed immediately.
self.vm.hmp_qemu_io("drive0", "aio_read 0 4096")
# Read 4KB again. The I/O limit has been exceeded so this
# request is throttled and a timer is set to wake it up.
self.vm.hmp_qemu_io("drive0", "aio_read 0 4096")
# Read from drive1. We're still over the I/O limit so this
# request is also throttled. There's no timer set in drive1
# because there's already one in drive0. Once the timer in
# drive0 fires and its throttled request is processed then the
# next request in the queue will be scheduled: this one.
self.vm.hmp_qemu_io("drive1", "aio_read 0 4096")
# At this point only the first 4KB have been read from drive0.
# The other requests are throttled.
self.assertEqual(self.blockstats('drive0')[0], 4096)
self.assertEqual(self.blockstats('drive1')[0], 0)
# Remove drive0 from the throttle group and disable its I/O limits.
# drive1 remains in the group with a throttled request.
params['bps_rd'] = 0
params['device'] = 'drive0'
result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **params)
self.assert_qmp(result, 'return', {})
# Removing the I/O limits from drive0 drains its pending request.
# The read request in drive1 is still throttled.
self.assertEqual(self.blockstats('drive0')[0], 8192)
self.assertEqual(self.blockstats('drive1')[0], 0)
# Advance the clock 5 seconds. This completes the request in drive1
self.vm.qtest("clock_step %d" % (5 * nsec_per_sec))
# Now all requests have been processed.
self.assertEqual(self.blockstats('drive0')[0], 8192)
self.assertEqual(self.blockstats('drive1')[0], 4096)
class ThrottleTestCoroutine(ThrottleTestCase):
test_img = "null-co://"
class ThrottleTestGroupNames(iotests.QMPTestCase):
test_img = "null-aio://"
max_drives = 3
def setUp(self):
self.vm = iotests.VM()
for i in range(0, self.max_drives):
self.vm.add_drive(self.test_img, "throttling.iops-total=100")
self.vm.launch()
def tearDown(self):
self.vm.shutdown()
def set_io_throttle(self, device, params):
params["device"] = device
result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **params)
self.assert_qmp(result, 'return', {})
def verify_name(self, device, name):
result = self.vm.qmp("query-block")
for r in result["return"]:
if r["device"] == device:
info = r["inserted"]
if name:
self.assertEqual(info["group"], name)
else:
self.assertFalse('group' in info)
return
raise Exception("No group information found for '%s'" % device)
def test_group_naming(self):
params = {"bps": 0,
"bps_rd": 0,
"bps_wr": 0,
"iops": 0,
"iops_rd": 0,
"iops_wr": 0}
# Check the drives added using the command line.
# The default throttling group name is the device name.
for i in range(self.max_drives):
devname = "drive%d" % i
self.verify_name(devname, devname)
# Clear throttling settings => the group name is gone.
for i in range(self.max_drives):
devname = "drive%d" % i
self.set_io_throttle(devname, params)
self.verify_name(devname, None)
# Set throttling settings using block_set_io_throttle and
# check the default group names.
params["iops"] = 10
for i in range(self.max_drives):
devname = "drive%d" % i
self.set_io_throttle(devname, params)
self.verify_name(devname, devname)
# Set a custom group name for each device
for i in range(3):
devname = "drive%d" % i
groupname = "group%d" % i
params['group'] = groupname
self.set_io_throttle(devname, params)
self.verify_name(devname, groupname)
# Put drive0 in group1 and check that all other devices remain
# unchanged
params['group'] = 'group1'
self.set_io_throttle('drive0', params)
self.verify_name('drive0', 'group1')
for i in range(1, self.max_drives):
devname = "drive%d" % i
groupname = "group%d" % i
self.verify_name(devname, groupname)
# Put drive0 in group2 and check that all other devices remain
# unchanged
params['group'] = 'group2'
self.set_io_throttle('drive0', params)
self.verify_name('drive0', 'group2')
for i in range(1, self.max_drives):
devname = "drive%d" % i
groupname = "group%d" % i
self.verify_name(devname, groupname)
# Clear throttling settings from drive0 check that all other
# devices remain unchanged
params["iops"] = 0
self.set_io_throttle('drive0', params)
self.verify_name('drive0', None)
for i in range(1, self.max_drives):
devname = "drive%d" % i
groupname = "group%d" % i
self.verify_name(devname, groupname)
class ThrottleTestRemovableMedia(iotests.QMPTestCase):
def setUp(self):
self.vm = iotests.VM()
if iotests.qemu_default_machine == 's390-ccw-virtio':
self.vm.add_device("virtio-scsi-ccw,id=virtio-scsi")
else:
self.vm.add_device("virtio-scsi-pci,id=virtio-scsi")
self.vm.launch()
def tearDown(self):
self.vm.shutdown()
def test_removable_media(self):
# Add a couple of dummy nodes named cd0 and cd1
result = self.vm.qmp("blockdev-add", driver="null-aio",
node_name="cd0")
self.assert_qmp(result, 'return', {})
result = self.vm.qmp("blockdev-add", driver="null-aio",
node_name="cd1")
self.assert_qmp(result, 'return', {})
# Attach a CD drive with cd0 inserted
result = self.vm.qmp("device_add", driver="scsi-cd",
id="dev0", drive="cd0")
self.assert_qmp(result, 'return', {})
# Set I/O limits
args = { "id": "dev0", "iops": 100, "iops_rd": 0, "iops_wr": 0,
"bps": 50, "bps_rd": 0, "bps_wr": 0 }
result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **args)
self.assert_qmp(result, 'return', {})
# Check that the I/O limits have been set
result = self.vm.qmp("query-block")
self.assert_qmp(result, 'return[0]/inserted/iops', 100)
self.assert_qmp(result, 'return[0]/inserted/bps', 50)
# Now eject cd0 and insert cd1
result = self.vm.qmp("blockdev-open-tray", id='dev0')
self.assert_qmp(result, 'return', {})
result = self.vm.qmp("blockdev-remove-medium", id='dev0')
self.assert_qmp(result, 'return', {})
result = self.vm.qmp("blockdev-insert-medium", id='dev0', node_name='cd1')
self.assert_qmp(result, 'return', {})
# Check that the I/O limits are still the same
result = self.vm.qmp("query-block")
self.assert_qmp(result, 'return[0]/inserted/iops', 100)
self.assert_qmp(result, 'return[0]/inserted/bps', 50)
# Eject cd1
result = self.vm.qmp("blockdev-remove-medium", id='dev0')
self.assert_qmp(result, 'return', {})
# Check that we can't set limits if the device has no medium
result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **args)
self.assert_qmp(result, 'error/class', 'GenericError')
# Remove the CD drive
result = self.vm.qmp("device_del", id='dev0')
self.assert_qmp(result, 'return', {})
if __name__ == '__main__':
iotests.main(supported_fmts=["raw"])
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