Depending on the value returned from QueueingHintFn, the scheduling queue changes how it queues each Pod:
  - if more than one QueueingHintFn returns QueueImmediately, it queues Pod to activeQ.
  - If no QueueingHintFn returns QueueImmediately and more than one plugin returns QueueAfterBackoff, it queues Pod to backoffQ if Pod is backing off, or to activeQ if Pod's backoff has already finished.

* Configurable etcd compaction frequency in GCE ([#59106](https://github.com/kubernetes/kubernetes/pull/59106), [@wojtek-t](https://github.com/wojtek-t))
* [GCE] Apiserver uses `InternalIP` as the most preferred kubelet address type by default. ([#59019](https://github.com/kubernetes/kubernetes/pull/59019), [@MrHohn](https://github.com/MrHohn))

  - apiserver_flowcontrol_current_r: R(the time of the last change in state of the queues)
  - apiserver_flowcontrol_dispatch_r: R(the time of the latest request dispatch)
  - apiserver_flowcontrol_latest_s: S(the request last dispatched) = R(when that request starts executing in the virtual world)
  - apiserver_flowcontrol_next_s_bounds: min and max next S among non-empty queues

- Kubeadm: make sure the etcd static pod startup probe uses /health?serializable=false while the liveness probe uses /health?serializable=true&exclude=NOSPACE. The NOSPACE exclusion would allow administrators to address space issues one member at a time. ([#110744](https://github.com/kubernetes/kubernetes/pull/110744), [@neolit123](ht...

- Scheduler: added metrics to record the number of pending pods in different queues ([#75501](https://github.com/kubernetes/kubernetes/pull/75501), [@Huang-Wei](https://github.com/Huang-Wei))

  - go_gc_cycles_total_gc_cycles_total
  - go_gc_heap_allocs_by_size_bytes
  - go_gc_heap_allocs_bytes_total
  - go_gc_heap_allocs_objects_total
  - go_gc_heap_frees_by_size_bytes
  - go_gc_heap_frees_bytes_total
  - go_gc_heap_frees_objects_total
  - go_gc_heap_goal_bytes
  - go_gc_heap_objects_objects
  - go_gc_heap_tiny_allocs_objects_total
  - go_gc_pauses_seconds
  - go_memory_classes_heap_free_bytes

* Added Group/Version/Kind and Action extension to OpenAPI Operations ([#44787](https://github.com/kubernetes/kubernetes/pull/44787), [@mbohlool](https://github.com/mbohlool))

* Make clear that meta.KindToResource is only a guess ([#45272](https://github.com/kubernetes/kubernetes/pull/45272), [@sttts](https://github.com/sttts))

* Add APIService conditions ([#43301](https://github.com/kubernetes/kubernetes/pull/43301), [@deads2k](https://github.com/deads2k))