openstack/cinder
Code Issues Proposed changes

Fix and unify capacity calculations

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This patch updates how cinder calculates it's free capacity.
The new calculations are based off of the queens cinder specs
that describes each of the capacity factors here:
https://specs.openstack.org/openstack/cinder-specs/specs/queens/provisioning-improvements.html

This patch updates the capacity filter to use the new capacity factors
calculations, which is also used by the capacity weigher.

The new calculate_capacity_factors describes each of the factors and
returns a dictionary of each of the factors as calculated.

Change-Id: Ic1b5737281e542d2782089a369e4b7941fc3d921
This commit is contained in:
Hemna 2022-02-28 13:53:20 -05:00
parent 1bebf4af85
commit 856d3e1080
7 changed files with 260 additions and 38 deletions
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50
cinder/scheduler/filters/capacity_filter.py
View File

@ -17,11 +17,10 @@
# under the License.
import math
from oslo_log import log as logging
from cinder.scheduler import filters
from cinder import utils
LOG = logging.getLogger(__name__)
@ -103,10 +102,6 @@ class CapacityFilter(filters.BaseBackendFilter):
"grouping_name": backend_state.backend_id})
return False
# Calculate how much free space is left after taking into account
# the reserved space.
free = free_space - math.floor(total * reserved)
# NOTE(xyang): If 'provisioning:type' is 'thick' in extra_specs,
# we will not use max_over_subscription_ratio and
# provisioned_capacity_gb to determine whether a volume can be
@ -118,18 +113,45 @@ class CapacityFilter(filters.BaseBackendFilter):
if provision_type == 'thick':
thin = False
thin_support = backend_state.thin_provisioning_support
if thin_support:
max_over_subscription_ratio = (
backend_state.max_over_subscription_ratio
)
else:
max_over_subscription_ratio = 1
# NOTE(hemna): this takes into consideration all major factors
# including reserved space, free_space (reported by driver),
# and over subscription ratio.
factors = utils.calculate_capacity_factors(
total_space,
free_space,
backend_state.provisioned_capacity_gb,
thin_support,
max_over_subscription_ratio,
backend_state.reserved_percentage,
thin
)
virtual_free_space = factors["virtual_free_capacity"]
LOG.debug("Storage Capacity factors %s", factors)
msg_args = {"grouping_name": backend_state.backend_id,
"grouping": grouping,
"requested": requested_size,
"available": free}
"available": virtual_free_space}
# Only evaluate using max_over_subscription_ratio if
# thin_provisioning_support is True. Check if the ratio of
# provisioned capacity over total capacity has exceeded over
# subscription ratio.
if (thin and backend_state.thin_provisioning_support and
backend_state.max_over_subscription_ratio >= 1):
provisioned_ratio = ((backend_state.provisioned_capacity_gb +
requested_size) / total)
provisioned_ratio = (
(backend_state.provisioned_capacity_gb + requested_size) / (
factors["total_available_capacity"]
)
)
LOG.debug("Checking provisioning for request of %s GB. "
"Backend: %s", requested_size, backend_state)
if provisioned_ratio > backend_state.max_over_subscription_ratio:
@ -149,14 +171,12 @@ class CapacityFilter(filters.BaseBackendFilter):
else:
# Thin provisioning is enabled and projected over-subscription
# ratio does not exceed max_over_subscription_ratio. The host
# passes if "adjusted" free virtual capacity is enough to
# passes if virtual free capacity is enough to
# accommodate the volume. Adjusted free virtual capacity is
# the currently available free capacity (taking into account
# of reserved space) which we can over-subscribe.
adjusted_free_virtual = (
free * backend_state.max_over_subscription_ratio)
msg_args["available"] = adjusted_free_virtual
res = adjusted_free_virtual >= requested_size
msg_args["available"] = virtual_free_space
res = virtual_free_space >= requested_size
if not res:
LOG.warning("Insufficient free virtual space "
"(%(available)sGB) to accommodate thin "
@ -179,7 +199,7 @@ class CapacityFilter(filters.BaseBackendFilter):
"grouping_name": backend_state.backend_id})
return False
if free < requested_size:
if virtual_free_space < requested_size:
LOG.warning("Insufficient free space for volume creation "
"on %(grouping)s %(grouping_name)s (requested / "
"avail): %(requested)s/%(available)s",

2
cinder/tests/unit/scheduler/test_capacity_weigher.py
View File

@ -114,7 +114,7 @@ class CapacityWeigherTestCase(test.TestCase):
{'volume_type': {'extra_specs': {'provisioning:type': 'thin'}},
'winner': 'host4'},
{'volume_type': {'extra_specs': {'provisioning:type': 'thick'}},
'winner': 'host2'},
'winner': 'host4'},
{'volume_type': {'extra_specs': {}},
'winner': 'host4'},
{'volume_type': {},

6
cinder/tests/unit/scheduler/test_host_filters.py
View File

@ -99,7 +99,7 @@ class CapacityFilterTestCase(BackendFiltersTestCase):
def test_filter_fails(self, _mock_serv_is_up):
_mock_serv_is_up.return_value = True
filt_cls = self.class_map['CapacityFilter']()
filter_properties = {'size': 100,
filter_properties = {'size': 121,
'request_spec': {'volume_id': fake.VOLUME_ID}}
service = {'disabled': False}
host = fakes.FakeBackendState('host1',
@ -282,7 +282,7 @@ class CapacityFilterTestCase(BackendFiltersTestCase):
def test_filter_thin_true_passes2(self, _mock_serv_is_up):
_mock_serv_is_up.return_value = True
filt_cls = self.class_map['CapacityFilter']()
filter_properties = {'size': 3000,
filter_properties = {'size': 2400,
'capabilities:thin_provisioning_support':
'<is> True',
'capabilities:thick_provisioning_support':
@ -462,7 +462,7 @@ class CapacityFilterTestCase(BackendFiltersTestCase):
def test_filter_reserved_thin_thick_true_fails(self, _mock_serv_is_up):
_mock_serv_is_up.return_value = True
filt_cls = self.class_map['CapacityFilter']()
filter_properties = {'size': 100,
filter_properties = {'size': 151,
'capabilities:thin_provisioning_support':
'<is> True',
'capabilities:thick_provisioning_support':

6
cinder/tests/unit/scheduler/test_host_manager.py
View File

@ -1029,7 +1029,7 @@ class HostManagerTestCase(test.TestCase):
"free": 18.01,
"allocated": 2.0,
"provisioned": 2.0,
"virtual_free": 37.02,
"virtual_free": 36.02,
"reported_at": 40000},
{"name_to_id": 'host1@backend1',
"type": "backend",
@ -1037,7 +1037,7 @@ class HostManagerTestCase(test.TestCase):
"free": 46.02,
"allocated": 4.0,
"provisioned": 4.0,
"virtual_free": 64.03,
"virtual_free": 63.03,
"reported_at": 40000}]
expected2 = [
@ -1055,7 +1055,7 @@ class HostManagerTestCase(test.TestCase):
"free": 46.02,
"allocated": 4.0,
"provisioned": 4.0,
"virtual_free": 95.04,
"virtual_free": 94.04,
"reported_at": 40000}]
def sort_func(data):

96
cinder/tests/unit/test_utils.py
View File

@ -1083,10 +1083,10 @@ class TestCalculateVirtualFree(test.TestCase):
'is_thin_lun': False, 'expected': 27.01},
{'total': 20.01, 'free': 18.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': False,
'is_thin_lun': True, 'expected': 37.02},
'is_thin_lun': True, 'expected': 36.02},
{'total': 20.01, 'free': 18.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': True,
'is_thin_lun': True, 'expected': 37.02},
'is_thin_lun': True, 'expected': 36.02},
{'total': 30.01, 'free': 28.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': True,
'is_thin_lun': False, 'expected': 27.01},
@ -1114,6 +1114,98 @@ class TestCalculateVirtualFree(test.TestCase):
self.assertEqual(expected, free_capacity)
@ddt.data(
{'total': 30.01, 'free': 28.01, 'provisioned': 2.0, 'max_ratio': 1.0,
'thin_support': False, 'thick_support': True,
'is_thin_lun': False, 'reserved_percentage': 5,
'expected_total_capacity': 30.01,
'expected_reserved_capacity': 1,
'expected_free_capacity': 28.01,
'expected_total_available_capacity': 29.01,
'expected_virtual_free': 27.01,
'expected_free_percent': 93.11,
'expected_provisioned_type': 'thick',
'expected_provisioned_ratio': 0.07},
{'total': 20.01, 'free': 18.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': False,
'is_thin_lun': True, 'reserved_percentage': 10,
'expected_total_capacity': 20.01,
'expected_reserved_capacity': 2,
'expected_free_capacity': 18.01,
'expected_total_available_capacity': 36.02,
'expected_virtual_free': 34.02,
'expected_free_percent': 94.45,
'expected_provisioned_type': 'thin',
'expected_provisioned_ratio': 0.06},
{'total': 20.01, 'free': 18.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': True,
'is_thin_lun': True, 'reserved_percentage': 20,
'expected_total_capacity': 20.01,
'expected_reserved_capacity': 4,
'expected_free_capacity': 18.01,
'expected_total_available_capacity': 32.02,
'expected_virtual_free': 30.02,
'expected_free_percent': 93.75,
'expected_provisioned_type': 'thin',
'expected_provisioned_ratio': 0.06},
{'total': 30.01, 'free': 28.01, 'provisioned': 2.0, 'max_ratio': 2.0,
'thin_support': True, 'thick_support': True,
'is_thin_lun': False, 'reserved_percentage': 10,
'expected_total_capacity': 30.01,
'expected_reserved_capacity': 3,
'expected_free_capacity': 28.01,
'expected_total_available_capacity': 27.01,
'expected_virtual_free': 25.01,
'expected_free_percent': 92.6,
'expected_provisioned_type': 'thick',
'expected_provisioned_ratio': 0.07},
)
@ddt.unpack
def test_utils_calculate_capacity_factors(
self, total, free, provisioned, max_ratio, thin_support,
thick_support, is_thin_lun, reserved_percentage,
expected_total_capacity,
expected_reserved_capacity,
expected_free_capacity,
expected_total_available_capacity,
expected_virtual_free,
expected_free_percent,
expected_provisioned_type,
expected_provisioned_ratio):
host_stat = {'total_capacity_gb': total,
'free_capacity_gb': free,
'provisioned_capacity_gb': provisioned,
'max_over_subscription_ratio': max_ratio,
'thin_provisioning_support': thin_support,
'thick_provisioning_support': thick_support,
'reserved_percentage': reserved_percentage}
factors = utils.calculate_capacity_factors(
host_stat['total_capacity_gb'],
host_stat['free_capacity_gb'],
host_stat['provisioned_capacity_gb'],
host_stat['thin_provisioning_support'],
host_stat['max_over_subscription_ratio'],
host_stat['reserved_percentage'],
is_thin_lun)
self.assertEqual(expected_total_capacity,
factors['total_capacity'])
self.assertEqual(expected_reserved_capacity,
factors['reserved_capacity'])
self.assertEqual(expected_free_capacity,
factors['free_capacity'])
self.assertEqual(expected_total_available_capacity,
factors['total_available_capacity'])
self.assertEqual(expected_virtual_free,
factors['virtual_free_capacity'])
self.assertEqual(expected_free_percent,
factors['free_percent'])
self.assertEqual(expected_provisioned_type,
factors['provisioned_type'])
self.assertEqual(expected_provisioned_ratio,
factors['provisioned_ratio'])
class Comparable(utils.ComparableMixin):
def __init__(self, value):

130
cinder/utils.py
View File

@ -715,14 +715,118 @@ def build_or_str(elements: Union[None, str, Iterable[str]],
return elements
def calculate_capacity_factors(total_capacity: float,
free_capacity: float,
provisioned_capacity: float,
thin_provisioning_support: bool,
max_over_subscription_ratio: float,
reserved_percentage: int,
thin: bool) -> dict:
"""Create the various capacity factors of the a particular backend.
Based off of definition of terms
cinder-specs/specs/queens/provisioning-improvements.html
Description of factors calculated where units of gb are Gibibytes.
reserved_capacity - The amount of space reserved from the total_capacity
as reported by the backend.
total_reserved_available_capacity - The total capacity minus reserved
capacity
total_available_capacity - The total capacity available to cinder
calculated from total_reserved_available_capacity (for thick) OR
for thin total_reserved_available_capacity max_over_subscription_ratio
calculated_free_capacity - total_available_capacity - provisioned_capacity
virtual_free_capacity - The calculated free capacity available to cinder
to allocate new storage.
For thin: calculated_free_capacity
For thick: the reported free_capacity can be less than the calculated
capacity, so we use free_capacity - reserved_capacity.
free_percent - the percentage of the virtual_free_capacity and
total_available_capacity is left over
provisioned_ratio - The ratio of provisioned storage to
total_available_capacity
:param total_capacity: The reported total capacity in the backend.
:type total_capacity: float
:param free_capacity: The free space/capacity as reported by the backend.
:type free_capacity: float
:param provisioned_capacity: as reported by backend or volume manager from
allocated_capacity_gb
:type provisioned_capacity: float
:param thin_provisioning_support: Is thin provisioning supported?
:type thin_provisioning_support: bool
:param max_over_subscription_ratio: as reported by the backend
:type max_over_subscription_ratio: float
:param reserved_percentage: the % amount to reserve as unavailable. 0-100
:type reserved_percentage: int, 0-100
:param thin: calculate based on thin provisioning if enabled by
thin_provisioning_support
:type thin: bool
:return: A dictionary of all of the capacity factors.
:rtype: dict
"""
total = float(total_capacity)
reserved = float(reserved_percentage) / 100
reserved_capacity = math.floor(total * reserved)
total_reserved_available = total - reserved_capacity
if thin and thin_provisioning_support:
total_available_capacity = (
total_reserved_available * max_over_subscription_ratio
)
calculated_free = total_available_capacity - provisioned_capacity
virtual_free = calculated_free
provisioned_type = 'thin'
else:
# Calculate how much free space is left after taking into
# account the reserved space.
total_available_capacity = total_reserved_available
calculated_free = total_available_capacity - provisioned_capacity
virtual_free = calculated_free
if free_capacity < calculated_free:
virtual_free = free_capacity
provisioned_type = 'thick'
if total_available_capacity:
provisioned_ratio = provisioned_capacity / total_available_capacity
free_percent = (virtual_free / total_available_capacity) * 100
else:
provisioned_ratio = 0
free_percent = 0
def _limit(x):
"""Limit our floating points to 2 decimal places."""
return round(x, 2)
return {
"total_capacity": total,
"free_capacity": free_capacity,
"reserved_capacity": reserved_capacity,
"total_reserved_available_capacity": _limit(total_reserved_available),
"max_over_subscription_ratio": (
max_over_subscription_ratio if provisioned_type == 'thin' else None
),
"total_available_capacity": _limit(total_available_capacity),
"provisioned_capacity": provisioned_capacity,
"calculated_free_capacity": _limit(calculated_free),
"virtual_free_capacity": _limit(virtual_free),
"free_percent": _limit(free_percent),
"provisioned_ratio": _limit(provisioned_ratio),
"provisioned_type": provisioned_type
}
def calculate_virtual_free_capacity(total_capacity: float,
free_capacity: float,
provisioned_capacity: float,
thin_provisioning_support: bool,
max_over_subscription_ratio: float,
reserved_percentage: float,
reserved_percentage: int,
thin: bool) -> float:
"""Calculate the virtual free capacity based on thin provisioning support.
"""Calculate the virtual free capacity based on multiple factors.
:param total_capacity: total_capacity_gb of a host_state or pool.
:param free_capacity: free_capacity_gb of a host_state or pool.
@ -738,18 +842,16 @@ def calculate_virtual_free_capacity(total_capacity: float,
:returns: the calculated virtual free capacity.
"""
total = float(total_capacity)
reserved = float(reserved_percentage) / 100
if thin and thin_provisioning_support:
free = (total * max_over_subscription_ratio
- provisioned_capacity
- math.floor(total * reserved))
else:
# Calculate how much free space is left after taking into
# account the reserved space.
free = free_capacity - math.floor(total * reserved)
return free
factors = calculate_capacity_factors(
total_capacity,
free_capacity,
provisioned_capacity,
thin_provisioning_support,
max_over_subscription_ratio,
reserved_percentage,
thin
)
return factors["virtual_free_capacity"]
def calculate_max_over_subscription_ratio(

8
releasenotes/notes/slug-b6a0fc3db0a2dd45.yaml Normal file
View File

@ -0,0 +1,8 @@
---
other:
- |
Unified how cinder calculates the virtual free storage space for a pool.
Previously Cinder had 2 different mechanisms for calculating the
virtual free storage. Now both the Capacity Filter and the Capacity
Weigher use the same mechanism, which is based upon the defined terms in
https://specs.openstack.org/openstack/cinder-specs/specs/queens/provisioning-improvements.html