DERP writes go via TCP and the host OS will have plenty of buffer space.
We've observed in the wild with a backed up TCP socket kernel side
buffers of >2.4MB. The DERP internal queue being larger causes an
increase in the probability that the contents of the backbuffer are
"dead letters" - packets that were assumed to be lost.
A first step to improvement is to size this queue only large enough to
avoid some of the initial connect stall problem, but not large enough
that it is contributing in a substantial way to buffer bloat /
dead-letter retention.
Updates tailscale/corp#31762
Signed-off-by: James Tucker <james@tailscale.com>
f5d3c59a92