From d11e62523e24822c1b131d8bfce4b6362986eddb Mon Sep 17 00:00:00 2001 From: tuexen Date: Thu, 24 Feb 2011 22:36:40 +0000 Subject: [PATCH] * Cleanup the code computing the retransmission timeout. * Fix an initialization bug for the scaled variance of the RTO. MFC after: 3 months. --- sys/netinet/sctp_structs.h | 10 ++-- sys/netinet/sctp_sysctl.c | 2 +- sys/netinet/sctputil.c | 104 ++++++++++++------------------------- 3 files changed, 39 insertions(+), 77 deletions(-) diff --git a/sys/netinet/sctp_structs.h b/sys/netinet/sctp_structs.h index d5cade710c3b..6503ec53d35d 100644 --- a/sys/netinet/sctp_structs.h +++ b/sys/netinet/sctp_structs.h @@ -245,7 +245,7 @@ struct sctp_nets { /* smoothed average things for RTT and RTO itself */ int lastsa; int lastsv; - int rtt; /* last measured rtt value in ms */ + uint64_t rtt; /* last measured rtt value in us */ unsigned int RTO; /* This is used for SHUTDOWN/SHUTDOWN-ACK/SEND or INIT timers */ @@ -254,6 +254,10 @@ struct sctp_nets { /* last time in seconds I sent to it */ struct timeval last_sent_time; + + /* JRS - struct used in HTCP algorithm */ + struct htcp htcp_ca; + int ref_count; /* Congestion stats per destination */ @@ -267,7 +271,6 @@ struct sctp_nets { uint32_t ecn_prev_cwnd; /* ECN prev cwnd at first ecn_echo seen in new * window */ uint32_t partial_bytes_acked; /* in CA tracks when to incr a MTU */ - uint32_t prev_rtt; /* tracking variables to avoid the aloc/free in sack processing */ unsigned int net_ack; unsigned int net_ack2; @@ -298,7 +301,6 @@ struct sctp_nets { uint32_t tos_flowlabel; struct timeval start_time; /* time when this net was created */ - struct timeval last_measured_rtt; uint32_t marked_retrans;/* number or DATA chunks marked for timer * based retransmissions */ uint32_t marked_fastretrans; @@ -348,8 +350,6 @@ struct sctp_nets { uint8_t RTO_measured; /* Have we done the first measure */ uint8_t last_hs_used; /* index into the last HS table entry we used */ uint8_t lan_type; - /* JRS - struct used in HTCP algorithm */ - struct htcp htcp_ca; uint32_t flowid; #ifdef INVARIANTS uint8_t flowidset; diff --git a/sys/netinet/sctp_sysctl.c b/sys/netinet/sctp_sysctl.c index 1863df9e9dcd..a048e23f9ab9 100644 --- a/sys/netinet/sctp_sysctl.c +++ b/sys/netinet/sctp_sysctl.c @@ -477,7 +477,7 @@ sctp_assoclist(SYSCTL_HANDLER_ARGS) xraddr.cwnd = net->cwnd; xraddr.flight_size = net->flight_size; xraddr.mtu = net->mtu; - xraddr.rtt = net->rtt; + xraddr.rtt = net->rtt / 1000; xraddr.start_time.tv_sec = (uint32_t) net->start_time.tv_sec; xraddr.start_time.tv_usec = (uint32_t) net->start_time.tv_usec; SCTP_INP_RUNLOCK(inp); diff --git a/sys/netinet/sctputil.c b/sys/netinet/sctputil.c index 30cc9edc887d..fec537663720 100644 --- a/sys/netinet/sctputil.c +++ b/sys/netinet/sctputil.c @@ -113,7 +113,7 @@ rto_logging(struct sctp_nets *net, int from) memset(&sctp_clog, 0, sizeof(sctp_clog)); sctp_clog.x.rto.net = (void *)net; - sctp_clog.x.rto.rtt = net->prev_rtt; + sctp_clog.x.rto.rtt = net->rtt / 1000; SCTP_CTR6(KTR_SCTP, "SCTP:%d[%d]:%x-%x-%x-%x", SCTP_LOG_EVENT_RTT, from, @@ -2475,9 +2475,8 @@ sctp_calculate_rto(struct sctp_tcb *stcb, * given an association and the starting time of the current RTT * period (in value1/value2) return RTO in number of msecs. */ - int calc_time = 0; - int o_calctime; - uint32_t new_rto = 0; + int32_t rtt; /* RTT in ms */ + uint32_t new_rto; int first_measure = 0; struct timeval now, then, *old; @@ -2497,95 +2496,58 @@ sctp_calculate_rto(struct sctp_tcb *stcb, /************************/ /* get the current time */ (void)SCTP_GETTIME_TIMEVAL(&now); - /* - * Record the real time of the last RTT for use in DC-CC. - */ - net->last_measured_rtt = now; - timevalsub(&net->last_measured_rtt, old); + timevalsub(&now, old); + /* store the current RTT in us */ + net->rtt = (uint64_t) 10000000 *(uint64_t) now.tv_sec + + (uint64_t) now.tv_usec; + + /* computer rtt in ms */ + rtt = net->rtt / 1000; /* Do we need to determine the lan type? */ - if ((local_lan_determine == SCTP_DETERMINE_LL_OK) && (net->lan_type == SCTP_LAN_UNKNOWN)) { - if ((net->last_measured_rtt.tv_sec) || - (net->last_measured_rtt.tv_usec > SCTP_LOCAL_LAN_RTT)) { + if ((local_lan_determine == SCTP_DETERMINE_LL_OK) && + (net->lan_type == SCTP_LAN_UNKNOWN)) { + if (net->rtt > SCTP_LOCAL_LAN_RTT) { net->lan_type = SCTP_LAN_INTERNET; } else { net->lan_type = SCTP_LAN_LOCAL; } } - /* compute the RTT value */ - if ((u_long)now.tv_sec > (u_long)old->tv_sec) { - calc_time = ((u_long)now.tv_sec - (u_long)old->tv_sec) * 1000; - if ((u_long)now.tv_usec > (u_long)old->tv_usec) { - calc_time += (((u_long)now.tv_usec - - (u_long)old->tv_usec) / 1000); - } else if ((u_long)now.tv_usec < (u_long)old->tv_usec) { - /* Borrow 1,000ms from current calculation */ - calc_time -= 1000; - /* Add in the slop over */ - calc_time += ((int)now.tv_usec / 1000); - /* Add in the pre-second ms's */ - calc_time += (((int)1000000 - (int)old->tv_usec) / 1000); - } - } else if ((u_long)now.tv_sec == (u_long)old->tv_sec) { - if ((u_long)now.tv_usec > (u_long)old->tv_usec) { - calc_time = ((u_long)now.tv_usec - - (u_long)old->tv_usec) / 1000; - } else if ((u_long)now.tv_usec < (u_long)old->tv_usec) { - /* impossible .. garbage in nothing out */ - goto calc_rto; - } else if ((u_long)now.tv_usec == (u_long)old->tv_usec) { - /* - * We have to have 1 usec :-D this must be the - * loopback. - */ - calc_time = 1; - } else { - /* impossible .. garbage in nothing out */ - goto calc_rto; - } - } else { - /* Clock wrapped? */ - goto calc_rto; - } /***************************/ /* 2. update RTTVAR & SRTT */ /***************************/ - net->rtt = o_calctime = calc_time; - /* this is Van Jacobson's integer version */ + /*- + * Compute the scaled average lastsa and the + * scaled variance lastsv as described in van Jacobson + * Paper "Congestion Avoidance and Control", Annex A. + * + * (net->lastsa >> SCTP_RTT_SHIFT) is the srtt + * (net->lastsa >> SCTP_RTT_VAR_SHIFT) is the rttvar + */ if (net->RTO_measured) { - calc_time -= (net->lastsa >> SCTP_RTT_SHIFT); /* take away 1/8th when - * shift=3 */ + rtt -= (net->lastsa >> SCTP_RTT_SHIFT); + net->lastsa += rtt; + if (rtt < 0) { + rtt = -rtt; + } + rtt -= (net->lastsv >> SCTP_RTT_VAR_SHIFT); + net->lastsv += rtt; if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_RTTVAR_LOGGING_ENABLE) { rto_logging(net, SCTP_LOG_RTTVAR); } - net->prev_rtt = o_calctime; - net->lastsa += calc_time; /* add 7/8th into sa when - * shift=3 */ - if (calc_time < 0) { - calc_time = -calc_time; - } - calc_time -= (net->lastsv >> SCTP_RTT_VAR_SHIFT); /* take away 1/4 when - * VAR shift=2 */ - net->lastsv += calc_time; - if (net->lastsv == 0) { - net->lastsv = SCTP_CLOCK_GRANULARITY; - } } else { /* First RTO measurment */ net->RTO_measured = 1; - net->lastsa = calc_time << SCTP_RTT_SHIFT; /* Multiply by 8 when - * shift=3 */ - net->lastsv = calc_time; - if (net->lastsv == 0) { - net->lastsv = SCTP_CLOCK_GRANULARITY; - } first_measure = 1; - net->prev_rtt = o_calctime; + net->lastsa = rtt << SCTP_RTT_SHIFT; + net->lastsv = (rtt / 2) << SCTP_RTT_VAR_SHIFT; if (SCTP_BASE_SYSCTL(sctp_logging_level) & SCTP_RTTVAR_LOGGING_ENABLE) { rto_logging(net, SCTP_LOG_INITIAL_RTT); } } -calc_rto: + if (net->lastsv == 0) { + net->lastsv = SCTP_CLOCK_GRANULARITY; + } new_rto = (net->lastsa >> SCTP_RTT_SHIFT) + net->lastsv; if ((new_rto > SCTP_SAT_NETWORK_MIN) && (stcb->asoc.sat_network_lockout == 0)) {