Before this fix, hint permutations such as:
permutation: [{11 true} {0101 true}]
Could result in merged hints of:
mergedHint: {01 true}
This was possible because both hints in the permutation container a "preferred"
allocation (i.e. the full set of NUMA nodes set in the affinity bitmask are
*required* to satisfy the allocation). With this in place, the simplified logic
we had simply kept the merged hint as preferred as well.
However, what we really want is to ensure that the merged hint is only
preferred if *true* alignment of all resources is possible (i.e. if all hints
in the permutation are preferred AND their affinities are exactly equal).
The only exception to this is if *no* topology information is provided by a
given hint provider. In this case, we assume alignment doesn't matter and only
consider the resources that actually have hints provided for them.
This changes the semantics of permutations of the form:
permutation: [{111 true} {011 true}]
To now result in the merged hint of:
mergedHint: {011 false}
Instead of:
mergedHint: {011 true}
This is arguably how it should always have been though (because a hint should
not be preferred if true alignment isn't possible), and two tests have had to
change to accomodate these new semantics.
This commit changes the merge function to implement the updated logic, adds a
test to verify it is functioning correctly, and updates the two tests mentioned
above to adjust to the new semantics.
Signed-off-by: Kevin Klues <kklues@nvidia.com>
- Initialize best Hint to TopologyHint{}
- Update checks.
- Move generic unit test case into policy specific tests and updated
expected outcome to reflect changes.
- 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.
- Update filterHints test to reflect changes in previous commit.
- Some common test cases achieve differing expected results based on
policy due to independent merge strategies. These cases are moved into
individual policy based test functions.
These changes make it so that a set of common test cases can be used for
all merge strategies, with specific test cases being able to be
specified on a policy-by-policy basis.
