Author: lstewart
Date: Tue Aug 21 02:17:06 2012
New Revision: 239474
URL: http://svn.freebsd.org/changeset/base/239474
Log:
MFC r239346:
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
Modified:
stable/9/sys/netinet/khelp/h_ertt.c
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/netinet/khelp/h_ertt.c
==============================================================================
--- stable/9/sys/netinet/khelp/h_ertt.c Tue Aug 21 00:05:44 2012
(r239473)
+++ stable/9/sys/netinet/khelp/h_ertt.c Tue Aug 21 02:17:06 2012
(r239474)
@@ -151,11 +151,13 @@ marked_packet_rtt(struct txseginfo *txsi
*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_t
*/
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_
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);
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