From ee24d3b8401985c99a4a1755765fe9332daee568 Mon Sep 17 00:00:00 2001 From: Lawrence Stewart Date: Fri, 17 Aug 2012 01:49:51 +0000 Subject: [PATCH] The TCP PAWS fix for kernels with fast tick rates (r231767) changed the TCP timestamp related stack variables to reference ms directly instead of ticks. The h_ertt(4) Khelp module relies on TCP timestamp information in order to calculate its enhanced RTT estimates, but was not updated as part of r231767. Consequently, h_ertt has not been calculating correct RTT estimates since r231767 was comitted, which in turn broke all delay-based congestion control algorithms because they rely on the h_ertt RTT estimates. Fix the breakage by switching h_ertt to use tcp_ts_getticks() in place of all previous uses of the ticks variable. This ensures all timestamp related variables in h_ertt use the same units as the TCP stack and therefore results in meaningful comparisons and RTT estimate calculations. Reported & tested by: Naeem Khademi (naeemk at ifi uio no) Discussed with: bz MFC after: 3 days --- sys/netinet/khelp/h_ertt.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/sys/netinet/khelp/h_ertt.c b/sys/netinet/khelp/h_ertt.c index 7ce195ce252d..13d15e04545a 100644 --- a/sys/netinet/khelp/h_ertt.c +++ b/sys/netinet/khelp/h_ertt.c @@ -151,11 +151,13 @@ marked_packet_rtt(struct txseginfo *txsi, struct ertt *e_t, struct tcpcb *tp, *prtt_bytes_adjust += *pmeasurenext_len; } else { if (mflag & FORCED_MEASUREMENT) { - e_t->markedpkt_rtt = ticks - *pmeasurenext + 1; + e_t->markedpkt_rtt = tcp_ts_getticks() - + *pmeasurenext + 1; e_t->bytes_tx_in_marked_rtt = e_t->bytes_tx_in_rtt + *pmeasurenext_len - *prtt_bytes_adjust; } else { - e_t->markedpkt_rtt = ticks - txsi->tx_ts + 1; + e_t->markedpkt_rtt = tcp_ts_getticks() - + txsi->tx_ts + 1; e_t->bytes_tx_in_marked_rtt = e_t->bytes_tx_in_rtt - *prtt_bytes_adjust; } @@ -349,7 +351,7 @@ ertt_packet_measurement_hook(int hhook_type, int hhook_id, void *udata, */ if (!e_t->dlyack_rx || multiack || new_sacked_bytes) { /* Make an accurate new measurement. */ - e_t->rtt = ticks - txsi->tx_ts + 1; + e_t->rtt = tcp_ts_getticks() - txsi->tx_ts + 1; if (e_t->rtt < e_t->minrtt || e_t->minrtt == 0) e_t->minrtt = e_t->rtt; @@ -477,7 +479,7 @@ ertt_add_tx_segment_info_hook(int hhook_type, int hhook_id, void *udata, tp->ts_offset; txsi->rx_ts = ntohl(to->to_tsecr); } else { - txsi->tx_ts = ticks; + txsi->tx_ts = tcp_ts_getticks(); txsi->rx_ts = 0; /* No received time stamp. */ } TAILQ_INSERT_TAIL(&e_t->txsegi_q, txsi, txsegi_lnk);