Now that the algorithm for balancing CPU distributions across NUMA nodes is
correct, this test actually behaves differently for the "packed" vs.
"distributed" allocation algorithms (as it should).
In the "packed" case we need to ensure that CPUs are allocated such that they
are packed onto cores. Since one CPU is already allocated from a core on NUMA
node 0, we want the next CPU to be its hyperthreaded pair (even though the
first available CPU id is on Socket 1).
In the "distributed" case, however, we want to ensure CPUs are allocated such
that we have an balanced distribution of CPUs across all NUMA nodes. This
points to allocating from Socket 1 if the only other CPU allocated has been
done on Socket 0.
To allow CPUs allocations to be packed onto full cores, one can allocate them
from the "distributed" algorithm with a 'cpuGroupSize' equal to the number of
hypthreads per core (in this case 2). We added an explicit test case for this,
demonstrating that we get the same result as the "packed" algorithm does, even
though the "distributed" algorithm is in use.
Signed-off-by: Kevin Klues <kklues@nvidia.com>
This fixes two related tests to better test our "balanced" distribution algorithm.
The first test originally provided an input with the following number of CPUs
available on each NUMA node:
Node 0: 16
Node 1: 20
Node 2: 20
Node 3: 20
It then attempted to distribute 48 CPUs across them with an expectation that
each of the first 3 NUMA nodes would have 16 CPUs taken from them (leaving Node
0 with no more CPUs in the end).
This would have resulted in the following amount of CPUs on each node:
Node 0: 0
Node 1: 4
Node 2: 4
Node 3: 20
Which results in a standard deviation of 7.6811
However, a more balanced solution would actually be to pull 16 CPUs from NUMA
nodes 1, 2, and 3, and leave 0 untouched, i.e.:
Node 0: 16
Node 1: 4
Node 2: 4
Node 3: 4
Which results in a standard deviation of 5.1961524227066
To fix this test we changed the original number of available CPUs to start with
4 less CPUs on NUMA node 3, and 2 more CPUs on NUMA node 0, i.e.:
Node 0: 18
Node 1: 20
Node 2: 20
Node 3: 16
So that we end up with a result of:
Node 0: 2
Node 1: 4
Node 2: 4
Node 3: 16
Which pulls the CPUs from where we want and results in a standard deviation of 5.5452
For the second test, we simply reverse the number of CPUs available for Nodes 0
and 3 as:
Node 0: 16
Node 1: 20
Node 2: 20
Node 3: 18
Which forces the allocation to happen just as it did for the first test, except
now on NUMA nodes 1, 2, and 3 instead of NUMA nodes 0,1, and 2.
Signed-off-by: Kevin Klues <kklues@nvidia.com>
This parameter ensures that CPUs are always allocated in groups of size
'cpuGroupSize'. This is important, for example, to ensure that all CPUs (i.e.
hyperthreads) from the same core are handed out together.
Signed-off-by: Kevin Klues <kklues@nvidia.com>
As part of this, pull out all of the existing "TakeByTopology" tests and have
them be called by the original TestTakeByTopologyNUMAPacked() as well as the
new TestTakeByTopologyNUMADistributed() test. In a subsequent commit, we will
add some tests that should differ between these two algorithms.
Signed-off-by: Kevin Klues <kklues@nvidia.com>
The first implements the original algorithm which packs CPUs onto NUMA nodes if
more than one NUMA node is required to satisfy the allocation. The second
disitributes CPUs across NUMA nodes if they can't all fit into one.
The "distributing" algorithm is currently a noop and just returns an error of
"unimplemented". A subsequent commit will add the logic to implement this
algorithm according to KEP 2902:
https://github.com/kubernetes/enhancements/tree/master/keps/sig-node/2902-cpumanager-distribute-cpus-policy-option
Signed-off-by: Kevin Klues <kklues@nvidia.com>
This batch of tests adds a fake topology on which each numa node
has multiple sockets. We didn't find yet a real HW topology in the wild
like this, but we need one to fully exercise the code.
So, until we find a HW topology, we add a fake one flipping
the NUMA/socket config of the existing xeon dual gold 6320.
Signed-off-by: Francesco Romani <fromani@redhat.com>
This batch of tests adds a real topology on which each physical socket
has multiple NUMA zones. Taken by a real dual xeon 6320 gold.
Signed-off-by: Francesco Romani <fromani@redhat.com>
The exisiting unit tests where performing subtests without
actually using the full features of the testing package
(https://pkg.go.dev/testing#hdr-Subtests_and_Sub_benchmarks)
Update them with fairly minimal changes. The patch is deceptively
large because we need to move the code inside a new block.
Signed-off-by: Francesco Romani <fromani@redhat.com>
