openstack
/
neutron
Code Issues Proposed changes

Reservations: Don't count usage if resource is unlimited 

If a resource is unlimited (ie: limit<0) then there is no need
to verify headroom for it. This also means that there no need for
counting it; therefore it is possible to save some DB operations
by skipping the count phase.

Change-Id: Ibe9ca8a1c29fb8ba12df187c25f8f9515968a54d
Related-blueprint: better-quotas
This commit is contained in:
Salvatore Orlando 2015-08-28 08:55:42 -07:00
parent 14ef151fe0
commit 3c9482eb78
1 changed files with 14 additions and 12 deletions
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26
neutron/db/quota/driver.py
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@ -153,6 +153,20 @@ class DbQuotaDriver(object):
# to a single node will be avaialable.
requested_resources = deltas.keys()
with db_api.autonested_transaction(context.session):
# get_tenant_quotes needs in input a dictionary mapping resource
# name to BaseResosurce instances so that the default quota can be
# retrieved
current_limits = self.get_tenant_quotas(
context, resources, tenant_id)
unlimited_resources = set([resource for (resource, limit) in
current_limits.items() if limit < 0])
# Do not even bother counting resources and calculating headroom
# for resources with unlimited quota
LOG.debug(("Resources %s have unlimited quota limit. It is not "
"required to calculated headroom "),
",".join(unlimited_resources))
requested_resources = (set(requested_resources) -
unlimited_resources)
# Gather current usage information
# TODO(salv-orlando): calling count() for every resource triggers
# multiple queries on quota usage. This should be improved, however
@ -164,11 +178,6 @@ class DbQuotaDriver(object):
(resource, resources[resource].count(
context, plugin, tenant_id, resync_usage=False)) for
resource in requested_resources)
# get_tenant_quotes needs in inout a dictionary mapping resource
# name to BaseResosurce instances so that the default quota can be
# retrieved
current_limits = self.get_tenant_quotas(
context, resources, tenant_id)
# Adjust for expired reservations. Apparently it is cheaper than
# querying everytime for active reservations and counting overall
# quantity of resources reserved
@ -179,13 +188,6 @@ class DbQuotaDriver(object):
for resource in requested_resources:
expired_reservations = expired_deltas.get(resource, 0)
total_usage = current_usages[resource] - expired_reservations
# A negative quota limit means infinite
if current_limits[resource] < 0:
LOG.debug(("Resource %(resource)s has unlimited quota "
"limit. It is possible to allocate %(delta)s "
"items."), {'resource': resource,
'delta': deltas[resource]})
continue
res_headroom = current_limits[resource] - total_usage
LOG.debug(("Attempting to reserve %(delta)d items for "
"resource %(resource)s. Total usage: %(total)d; "