Previously, the verious Merge() policies of the TopologyManager all
eturned their own lifecycle.PodAdmitResult result. However, for
consistency in any failed admits, this is better handled in the
top-level Topology manager, with each policy only returning a boolean
about whether or not they would like to admit the pod or not. This
commit changes the semantics to match this logic.
- Move remaining logic from mergeProvidersHints to generic top level
mergeFilteredHints function.
- Add numaNodes as parameter in order to make generic.
- Move single NUMA node specific check to single-numa-node Merge
function.
- Move initial 'filtering' functionality to generic function
filterProvidersHints level policy.go.
- Call new function from top level Merge function.
- Rename some variables/parameters to reflect changes.
The logic has been updated to match the logic of the best-effort policy
except in two places:
1) The hint filtering frunction has been updated to allow "don't care"
hints encoded with a `nil` affinity mask, to pass through the filter in
addition to hints that have just a single NUMA bit set.
2) After calculating the `bestHint` we transform "don't care" affinities
encoded as having all NUMA bits set in their affinity masks into "don't
care" affinities encoded as `nil`.
- Initialize best Hint to TopologyHint{}
- Update checks.
- Move generic unit test case into policy specific tests and updated
expected outcome to reflect changes.
- Restructure function
- Remove bug fix for catching {nil true} - To be fixed in later commit
- Restore unit tests to original state for testing filterHints
- Best Effort Policy: Return hint with nil affinity as opposed to
defaultAffinity when provider has no preference for NUMA affinty or no
possible NUMA affinities.
- Single NUMA Node Policy: Remove defaultHint from mergeProvidersHints.
Instead return appropriate TopologyHint where required.
- Update unit tests to reflect changes. Some test cases moved into
individual policy test functions due to differing returned affinties
per policy.
- Remove getHintMatch method.
- Replace with simplified versions of mergePermutation and
iterateAllProviderTopologyHints methods - as used in best-effort.
- Remove getHintMatch unit tests.
- Only append valid preferred-true hints to filtered
- Return true if allResourceHints only consist of
nil-affinity/preferred-true hints: {nil true}, update defaultHint
preference accordingly.
Explanation taken from original commit:
- Change the current method of finding the best hint.
Instead of going over all permutations, sort the hints and find
the narrowest hint common to all resources.
- Break out early when merging to a preferred hint is not possible
- Remove need to pass policy and numaNodes as arguments
- Remove PolicySingleNUMANode special case check in policy_best_effort
- Add mergeProviderHints base to policy_single_numa_node for upcoming
commit
This abstraction moves the responsibility of merging topology hints to
the individual policies themselves. As part of this, it removes the
CanAdmitPodResult() API from the policy abstraction, and rolls it into a
second return value from Merge()
This patch fixes an issue where best-effort pods were not admitted
to the node if the single-numa-node policy was set.
This was because the Admit policy in single-numa-node policy does
not admit any pod where the hint is anything but single NUMA node. The 'best hint' in this case is {<set bits for num. Numa Nodes on machine>, true}
So on a machine with 2 NUMA nodes the best hint for a best-effort pod is {11,true} as best-effort pods have no Topology preferences.
The single-numa-node policy fails any pod with a not preferred hint OR a hint where > 1 bits are set, thus the above example resulting in termintaed pods with a Topology Affinity Error.
This is a short term fix for the single-numa-node policy, as there will be code refactoring for the 1.17 release.
