diff options
Diffstat (limited to 'sys/netinet/tcp_input.c')
| -rw-r--r-- | sys/netinet/tcp_input.c | 40 |
1 files changed, 20 insertions, 20 deletions
diff --git a/sys/netinet/tcp_input.c b/sys/netinet/tcp_input.c index 6ae41d7a5bd..ee964acbcdf 100644 --- a/sys/netinet/tcp_input.c +++ b/sys/netinet/tcp_input.c @@ -1,4 +1,4 @@ -/* $OpenBSD: tcp_input.c,v 1.181 2005/01/10 23:53:49 mcbride Exp $ */ +/* $OpenBSD: tcp_input.c,v 1.182 2005/02/27 13:22:56 markus Exp $ */ /* $NetBSD: tcp_input.c,v 1.23 1996/02/13 23:43:44 christos Exp $ */ /* @@ -940,7 +940,7 @@ after_listen: /* make sure ts_ecr is sensible */ rtt_test = tcp_now - opti.ts_ecr; - if (rtt_test < 0 || rtt_test > (TCP_RTT_MAX - 1)) + if (rtt_test < 0 || rtt_test > TCP_RTT_MAX) opti.ts_ecr = 0; } @@ -1002,7 +1002,7 @@ after_listen: */ ++tcpstat.tcps_predack; if (opti.ts_present && opti.ts_ecr) - tcp_xmit_timer(tp, tcp_now-opti.ts_ecr+1); + tcp_xmit_timer(tp, tcp_now - opti.ts_ecr); else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) tcp_xmit_timer(tp, @@ -1764,7 +1764,7 @@ trimthenstep6: * Recompute the initial retransmit timer. */ if (opti.ts_present && opti.ts_ecr) - tcp_xmit_timer(tp, tcp_now-opti.ts_ecr+1); + tcp_xmit_timer(tp, tcp_now - opti.ts_ecr); else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); @@ -2804,30 +2804,32 @@ tcp_xmit_timer(tp, rtt) short delta; short rttmin; - --rtt; if (rtt < 0) rtt = 0; - if (rtt > TCP_RTT_MAX) + else if (rtt > TCP_RTT_MAX) rtt = TCP_RTT_MAX; tcpstat.tcps_rttupdated++; if (tp->t_srtt != 0) { /* - * srtt is stored as fixed point with 3 bits after the - * binary point (i.e., scaled by 8). The following magic + * delta is fixed point with 2 (TCP_RTT_BASE_SHIFT) bits + * after the binary point (scaled by 4), whereas + * srtt is stored as fixed point with 5 bits after the + * binary point (i.e., scaled by 32). The following magic * is equivalent to the smoothing algorithm in rfc793 with * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed - * point). Adjust rtt to origin 0. + * point). */ - delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); + delta = (rtt << TCP_RTT_BASE_SHIFT) - + (tp->t_srtt >> TCP_RTT_SHIFT); if ((tp->t_srtt += delta) <= 0) - tp->t_srtt = 1; + tp->t_srtt = 1 << TCP_RTT_BASE_SHIFT; /* * We accumulate a smoothed rtt variance (actually, a * smoothed mean difference), then set the retransmit * timer to smoothed rtt + 4 times the smoothed variance. - * rttvar is stored as fixed point with 2 bits after the - * binary point (scaled by 4). The following is + * rttvar is stored as fixed point with 4 bits after the + * binary point (scaled by 16). The following is * equivalent to rfc793 smoothing with an alpha of .75 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces * rfc793's wired-in beta. @@ -2836,15 +2838,16 @@ tcp_xmit_timer(tp, rtt) delta = -delta; delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); if ((tp->t_rttvar += delta) <= 0) - tp->t_rttvar = 1; + tp->t_rttvar = 1 << TCP_RTT_BASE_SHIFT; } else { /* * No rtt measurement yet - use the unsmoothed rtt. * Set the variance to half the rtt (so our first * retransmit happens at 3*rtt). */ - tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); - tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); + tp->t_srtt = (rtt + 1) << (TCP_RTT_SHIFT + TCP_RTT_BASE_SHIFT); + tp->t_rttvar = (rtt + 1) << + (TCP_RTTVAR_SHIFT + TCP_RTT_BASE_SHIFT - 1); } tp->t_rtttime = 0; tp->t_rxtshift = 0; @@ -2860,10 +2863,7 @@ tcp_xmit_timer(tp, rtt) * statistical, we have to test that we don't drop below * the minimum feasible timer (which is 2 ticks). */ - if (tp->t_rttmin > rtt + 2) - rttmin = tp->t_rttmin; - else - rttmin = rtt + 2; + rttmin = min(max(rtt + 2, tp->t_rttmin), TCPTV_REXMTMAX); TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), rttmin, TCPTV_REXMTMAX); /* |