svn commit: r362225 - head/sys/netinet/tcp_stacks
Randall Stewart
rrs at FreeBSD.org
Tue Jun 16 12:26:24 UTC 2020
Author: rrs
Date: Tue Jun 16 12:26:23 2020
New Revision: 362225
URL: https://svnweb.freebsd.org/changeset/base/362225
Log:
So it turns out rack has a shortcoming in dup-ack counting. It counts the dupacks but
then does not properly respond to them. This is because a few missing bits are not present.
BBR actually does properly respond (though it also sends a TLP which is interesting and
maybe something to fix)..
Sponsored by: Netflix Inc.
Differential Revision: https://reviews.freebsd.org/D25294
Modified:
head/sys/netinet/tcp_stacks/rack.c
Modified: head/sys/netinet/tcp_stacks/rack.c
==============================================================================
--- head/sys/netinet/tcp_stacks/rack.c Tue Jun 16 12:21:55 2020 (r362224)
+++ head/sys/netinet/tcp_stacks/rack.c Tue Jun 16 12:26:23 2020 (r362225)
@@ -4588,7 +4588,7 @@ activate_rxt:
goto activate_rxt;
}
/* Convert from ms to usecs */
- if (rsm->r_flags & RACK_SACK_PASSED) {
+ if ((rsm->r_flags & RACK_SACK_PASSED) || (rsm->r_dupack >= DUP_ACK_THRESHOLD)) {
if ((tp->t_flags & TF_SENTFIN) &&
((tp->snd_max - tp->snd_una) == 1) &&
(rsm->r_flags & RACK_HAS_FIN)) {
@@ -6237,7 +6237,7 @@ rack_log_output(struct tcpcb *tp, struct tcpopt *to, i
* or FIN if seq_out is adding more on and a FIN is present
* (and we are not resending).
*/
- if ((th_flags & TH_SYN) && (seq_out == tp->iss))
+ if ((th_flags & TH_SYN) && (seq_out == tp->iss))
len++;
if (th_flags & TH_FIN)
len++;
@@ -8190,6 +8190,7 @@ rack_strike_dupack(struct tcp_rack *rack)
rsm->r_dupack++;
if (rsm->r_dupack >= DUP_ACK_THRESHOLD) {
rack->r_wanted_output = 1;
+ rack->r_timer_override = 1;
rack_log_retran_reason(rack, rsm, __LINE__, 1, 3);
} else {
rack_log_retran_reason(rack, rsm, __LINE__, 0, 3);
@@ -11359,7 +11360,8 @@ check_it:
if (rsm->r_flags & RACK_ACKED) {
return (NULL);
}
- if ((rsm->r_flags & RACK_SACK_PASSED) == 0) {
+ if (((rsm->r_flags & RACK_SACK_PASSED) == 0) &&
+ (rsm->r_dupack < DUP_ACK_THRESHOLD)) {
/* Its not yet ready */
return (NULL);
}
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