Computing EndpointChanges is a relatively expensive operation for
kube-proxy when Endpoint Slices are used. This had been computed on
every EndpointSlice update which became quite inefficient at high levels
of scale when multiple EndpointSlice update events would be triggered
before a syncProxyRules call.
Profiling results showed that computing this on each update could
consume ~80% of total kube-proxy CPU utilization at high levels of
scale. This change reduced that to as little as 3% of total kube-proxy
utilization at high levels of scale.
It's worth noting that the difference is minimal when there is a 1:1
relationship between EndpointSlice updates and proxier syncs. This is
primarily beneficial when there are many EndpointSlice updates between
proxier sync loops.
The detectStaleConnections function in kube-proxy is very expensive in
terms of CPU utilization. The results of this function are only actually
used for UDP ports. This adds a protocol attribute to ServicePortName to
make it simple to only run this function for UDP connections. For
clusters with primarily TCP connections this can improve kube-proxy
performance by 2x.
The .IP() call that was previously used for sorting resulted in a call
to netutil to parse an IP out of an IP:Port string. This was very slow
and resulted in this sort taking up ~50% of total CPU util for
kube-proxy.
This should fix a bug that could break masters when the EndpointSlice
feature gate was enabled. This was all tied to how the apiserver creates
and manages it's own services and endpoints (or in this case endpoint
slices). Consumers of endpoint slices also need to know about the
corresponding service. Previously we were trying to set an owner
reference here for this purpose, but that came with potential downsides
and increased complexity. This commit changes behavior of the apiserver
endpointslice integration to set the service name label instead of owner
references, and simplifies consumer logic to reference that (both are
set by the EndpointSlice controller).
Additionally, this should fix a bug with the EndpointSlice GenerateName
value that had previously been set with a "." as a suffix.
