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* Say what adopting the link took, and how it fares against ngtcp2 (102)eunhhu2026-09-291-0/+124
| | | | | | | | | | | | | | | | | | 102: the spec (012) and a receiver written from it alone; the four holes writing it found (REFUSED, the record's size, a peer's run places, the memo's places beside) and the credit M6 showed fixed at 1,024 records; M6 with ngtcp2 as a third, two rounds. Under reordering Pure carries the most (45 Mbit/s; ngtcp2 29-47, quinn 1-2), under random loss the three are the same, on a clean bottleneck Pure carries 3-5 % less (its framing, some 112 B a packet to QUIC's 41), and where loss and reordering meet ngtcp2 carries 1.3-3.6 times as much: undoing a loss it took for reordering, it restores the window a real loss had cut too (its log: 22 of 34 undos past the window before the last cut; none without reordering). Shares beside TCP stay within 25 %. 011 and the status table say so; 012 also says that a receiver answers within 25 ms (a sender's PTO counts on it), that a shape and a record's bytes are the app's, and why a packet of the past does no harm.
* Put ngtcp2 beside quinn in M6, as it is in M5eunhhu2026-09-291-21/+40
| | | | | | | | | drain.c takes a rate and seconds as quinn's client does (paced messages stamped with the time they were written, and no more written past the seconds), and its service writes quinn's line for each stream: the messages read in each 100 ms and how long they took. 020's run.py runs it as a third, on port 40005 behind the same bottleneck, and --who picks whom to run.
* Keep a sender's congestion state as one, so an episode undoes it wholeeunhhu2026-09-291-2/+2
| | | | | | | | The window, threshold, the start of recovery and CUBIC's four values were fields of their own, and an episode of congestion events copied each of the seven aside and back. Now they are one Congestion: an episode keeps a copy, and undoing it takes the copy back, the window grown since kept. test-link's results and the M6 simulator's are the same to the byte.
* Measure a link on paths of loss, reordering and a bottleneck, against quinn ↵eunhhu2026-09-291-0/+126
| | | | | | | | | | (097) M6 of design 011: with a 50 Mbit/s bottleneck, a link carries 21-41 times quinn's goodput when packets reorder, the same under random loss, and 1.3-3.5 times with both; its p99 at 50 records a second is the same or shorter; beside TCP CUBIC it takes 0.48-0.55 of the path, inside the guardrail. Only on a clean path is it 3-5% below quinn.
* Let M6's path waver by 1 ms when flows share it, and count from 20 s of 60eunhhu2026-09-291-6/+9
| | | | | | | | With a fixed delay the drop-tail queue dropped one flow's packets eight times as often as the other's by their phases alone (Floyd and Jacobson, 1992): Pure took 0.63-0.77 of the path from TCP and 0.69 from quinn, 0.47 from itself, and 0.49 under fq_codel. With 1 ms of jitter it takes 0.53 at an RTT of 20 ms.
* Record one round of M6 with the path's MTU found, before pacing (020)eunhhu2026-09-291-0/+42
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* Let the M6 simulator queue records at a rate and time each oneeunhhu2026-09-291-5/+33
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* Start M6's flows together, each a process, and count their shares from 10 seunhhu2026-09-291-26/+63
| | | | | | The TCP flow started first and in a thread of the runner; two TCP flows split 0.31 to 0.56. Now every flow is a process started at once, run 40 s, counted from 10 s on.
* Find how large a packet the path carries: 1,452 bytes once a probe is ↵eunhhu2026-09-291-2/+2
| | | | | | | | | | | | | | | acknowledged A link starts at 1,200 bytes; once an RTT is known it sends a PING padded to 1,452 (DPLPMTUD, RFC 8899), alone and with the don't-fragment bit, and uses that size once it is acknowledged. A probe lost is no congestion; it is tried again a second on, three times, then ten minutes on. GSO is asked for each burst (a control message), not the socket, so a packet sent alone is never cut. CUBIC counts in the datagram. On loopback packets fall by 19-27%; the CPU a record falls 13% at 1 KiB and 7% at 16 KiB; in the simulator of a 50 Mbit/s path with 1% loss the goodput rises from 6.1 to 7.0 Mbit/s (5%: 2.3 to 3.0).
* Record M6 with records in parts and no path MTU yet (020)eunhhu2026-09-291-0/+126
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* Queue only the way to the receivers behind M6's bottleneckeunhhu2026-09-291-15/+26
| | | | | | | | tbf with netem under it lost tbf's queue (netem became it), and the answers queued behind the data. Now each way has its netem, the way to the receivers' ports then a tbf whose queue holds a round trip; the way back does not queue. transport.c takes its listener's port (TRANSPORT_PORT).
* Measure a link on a path of loss, reordering and a bottleneck (M6 harness)eunhhu2026-09-291-0/+247
| | | | | | | | | 020-lossy-paths/run.py runs each case in an unprivileged namespace: a 50 Mbit/s tbf bottleneck under netem's delay, jitter and loss, both ways. A link may send without UDP GSO (pure_link_gso), as netem takes a burst as one packet; quinn the same (QUIC_GSO=0). transport.c and the quinn harness give the records handed over in each 100 ms, and at a steady rate the time each took; TCP CUBIC flows run beside them.
* Wait for late packets, undo what they cost, and grow as CUBICeunhhu2026-09-291-0/+165
A packet called lost stays known a while; acknowledged after all, it came late: what it carried counts as received, the reordering awaited grows (later packets acknowledged, and time past the RTT, as RACK), and an episode of congestion events whose losses all came late is undone. The window grows only when it was used (RFC 9002 7.8), and congestion avoidance is CUBIC (RFC 9438), as quinn's. In a path of 50 Mbit/s whose packets reorder by up to 5 ms, with no loss, a link carried 1.5 Mbit/s at an RTT of 20 ms and 10 at 100 ms; now 43.6 and 40.1, as without reordering (research/experiments/020-lossy-paths, virtual time). With 1% random loss: 4.9 to 6.1 at 20 ms, 1.0 to 1.3 at 100 ms. The transport's CPU a record is unchanged.