In order to implement the `full-pcpus-only` cpumanager policy option,
we leverage the implementation of the algorithm which picks CPUs.
By design, CPUs are taken from the biggest chunk available (socket
or NUMA zone) to physical cores, down to single cores.
Leveraging this, if the requested CPU count is a multiple of the SMT
level (commonly 2), we're guaranteed that only full physical cores
will be taken.
The hidden assumption here is this holds true by construction iff
the user reserved CPUs (if any) considering full physical CPUs.
IOW, if the user did intentionally or mistakely reserve single threads
which are no core siblings[1], then the simple check we implemented
is not sufficient.
A easy example can probably outline this better. With this setup:
cores: [(0, 4), (1, 5), (2, 6), (3, 8)] (in parens: thread siblings).
SMT level: 2 (each tuple is 2 elements)
Reserved CPUs: 0,1 (explicit pick using `--reserved-cpus`)
A container then requests 6 cpus. full-pcpus-only check: 6 % 2 == 0. Passed.
The CPU allocator will take first full cores, (2,6) and (3,8), and will
then pick the remaining single CPUs. The allocation will succeed, but
it's incorrect.
We can fix this case with a stricter precheck.
We need to additionally consider all the core siblings of the reserved
CPUs as unavailable when computing the free cpus, before to start the
actual allocation. Doing so, we fall back in the intended behavior, and
by construction all possible CPUs allocation whose number is multiple
of the SMT level are now correct again.
+++
[1] or thread siblings in the linux parlance, in any case:
hyperthread siblings of the same physical core
Signed-off-by: Francesco Romani <fromani@redhat.com>
hack/pin-dependency.sh github.com/moby/ipvs v1.1.0
- go to a fixed tag for `vishvananda/netns`
- no more references to `pkg/errors`
Signed-off-by: Davanum Srinivas <davanum@gmail.com>
While refactoring the backoff manager to simplify and unify the code
in wait a race condition was encountered in
TestSharedInformerWatchDisruption. The new implementation failed
because the fake clock was not propagated to the backoff managers
when the reflector was used in a controller. After ensuring the
mangaers, reflector, controller, and informer shared the same
clock the test needed was updated to avoid the race condition by
advancing the fake clock and adding real sleeps to wait for
asynchronous propagation of the various goroutines in the controller.
Due to the deep structure of informers it is difficult to inject
hooks to avoid having to perform sleeps. At a minimum the FakeClock
interface should allow a caller to determine the number of waiting
timers (to avoid the first sleep).
Remove dependencies on internal fieldmanager for admission things. This
is preparing for moving fieldmanager out, but the admission part will
stay here, so it can't depend directly on internal.
