RustDesk 691830fe89 bump webrtc: revert the T3-rtx probe recovery (#16121) ...

The probe recovery merged as 692113c87 cost two to four times the p99 on the
workload a remote desktop actually has, and the fork now reverts it: `sctp/src`
returns to 48100bf1, the revision this repository shipped in #15684, with the
benchmark harness and its corrections kept.

It was justified on a fixed frame rate. Nothing is sent while the screen holds
still - the capturer answers WouldBlock and the loop sends nothing - so typing,
reading and clicking are short bursts with silence between them, and a steady
frame rate is what playing video or dragging a window looks like and nothing
else. The difference matters because a steady rate hides the whole effect: the
next frame's SACK exposes a loss whatever the recovery logic does. Measured on
bursts with gaps, after correcting two faults in the harness itself, p99 in ms
for the two seeds:

                          sparse RTT70   sparse RTT150
    48100bf1  09-06 00:06   200 / 208      407 / 507
    b221f13b  09-06 14:00   328 / 804      737 / 826

On a fixed frame rate the two are within noise of each other, which is why this
was not caught. KCP is 138/130 and 257/250 on those rows, ahead of both.

What is given up: a tail loss of exactly four packets recovers in 140 ms rather
than 229, and an idle sender's backlog after a stall offers 1.58x the bytes
rather than 1.08x. A five-packet tail improves, 292 ms to 232.


Claude-Session: https://claude.ai/code/session_019aokqJuhjvB3kijXtAg5Ns

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

2026-09-08 23:31:05 +08:00

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