Originally identified by Coder and documented in their blog post, this
implementation differs slightly as our link endpoint was introduced for
a different purpose, but the behavior is the same: apply backpressure
rather than dropping packets. This reduces the negative impact of large
packet count bursts substantially. An alternative would be to swell the
size of the channel buffer substantially, however that's largely just
moving where buffering occurs and may lead to reduced signalling back to
lower layer or upstream congestion controls.
Updates #9707
Updates #10408
Updates #12393
Updates tailscale/corp#24483
Updates tailscale/corp#25169
Signed-off-by: James Tucker <james@tailscale.com>
4903d6c80b