Merge branch 'tcp-backlog-processing-optims'

Eric Dumazet says:

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tcp: backlog processing optims

First patches are mostly preparing the ground for the last one.

Last patch of the series implements sort of ACK reduction
only for the cases a TCP receiver is under high stress,
which happens for high throughput flows.

This gives us a ~20% increase of single TCP flow (100Gbit -> 120Gbit)
====================

Link: https://lore.kernel.org/r/20230911170531.828100-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>