Measure a link on a path of loss, reordering and a bottleneck (M6 harness)

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.

1 files changed, 4 insertions, 0 deletions

diff --git a/link/link.h b/link/link.h
index 5237262..afe1430 100644
--- a/link/link.h
+++ b/link/link.h
@@ -22,6 +22,10 @@ bool pure_link_queue(PureLink *, uint64_t seq, const unsigned char *bytes, size_
 uint64_t pure_link_queued(PureLink *);
 /* The last number the receiver saved; any thread. */
 uint64_t pure_link_delivered(PureLink *);
+/* Packets go in bursts with UDP GSO where the system has it (at first);
+ * off, each in a call of its own: for a path whose queues take a burst as
+ * one packet (netem does). Before pure_link_start. */
+void pure_link_gso(PureLink *, bool on);
 /* Send on a thread of the link's own, calling notify when more was saved. */
 bool pure_link_start(PureLink *, void (*notify)(void *), void *context, char *error, size_t size);
 void pure_link_counts(PureLink *, PureLinkCounts *);