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Delete #ifdef notdef blocks containing old method of srtt calculation.
Requested by: davidg
This commit is contained in:
Garrett Wollman
parent
93902408b8
commit
a2352fc148
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=15396
@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
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* $Id: tcp_input.c,v 1.41 1996/04/04 10:46:39 phk Exp $
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* $Id: tcp_input.c,v 1.42 1996/04/09 07:01:51 pst Exp $
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*/
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#ifndef TUBA_INCLUDE
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@ -1831,47 +1831,6 @@ tcp_xmit_timer(tp, rtt)
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register struct tcpcb *tp;
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short rtt;
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{
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#ifdef notdef
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register short delta;
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tcpstat.tcps_rttupdated++;
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tp->t_rttupdated++;
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if (tp->t_srtt != 0) {
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/*
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* srtt is stored as fixed point with 3 bits after the
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* binary point (i.e., scaled by 8). The following magic
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* is equivalent to the smoothing algorithm in rfc793 with
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* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
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* point). Adjust rtt to origin 0.
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*/
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delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
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if ((tp->t_srtt += delta) <= 0)
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tp->t_srtt = 1;
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/*
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* We accumulate a smoothed rtt variance (actually, a
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* smoothed mean difference), then set the retransmit
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* timer to smoothed rtt + 4 times the smoothed variance.
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* rttvar is stored as fixed point with 2 bits after the
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* binary point (scaled by 4). The following is
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* equivalent to rfc793 smoothing with an alpha of .75
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* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
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* rfc793's wired-in beta.
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*/
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if (delta < 0)
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delta = -delta;
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delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
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if ((tp->t_rttvar += delta) <= 0)
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tp->t_rttvar = 1;
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} else {
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/*
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* No rtt measurement yet - use the unsmoothed rtt.
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* Set the variance to half the rtt (so our first
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* retransmit happens at 3*rtt).
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*/
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tp->t_srtt = rtt << TCP_RTT_SHIFT;
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tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
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}
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#else /* Peterson paper */
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register int delta;
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tcpstat.tcps_rttupdated++;
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@ -1914,7 +1873,6 @@ tcp_xmit_timer(tp, rtt)
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tp->t_srtt = rtt << TCP_RTT_SHIFT;
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tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
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}
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#endif
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tp->t_rtt = 0;
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tp->t_rxtshift = 0;
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@ -1929,13 +1887,8 @@ tcp_xmit_timer(tp, rtt)
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* statistical, we have to test that we don't drop below
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* the minimum feasible timer (which is 2 ticks).
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*/
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#ifdef notdef
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TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
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tp->t_rttmin, TCPTV_REXMTMAX);
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#else /* Peterson */
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TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
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max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
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#endif
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/*
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* We received an ack for a packet that wasn't retransmitted;
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
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* $Id: tcp_input.c,v 1.41 1996/04/04 10:46:39 phk Exp $
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* $Id: tcp_input.c,v 1.42 1996/04/09 07:01:51 pst Exp $
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*/
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#ifndef TUBA_INCLUDE
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@ -1831,47 +1831,6 @@ tcp_xmit_timer(tp, rtt)
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register struct tcpcb *tp;
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short rtt;
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{
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#ifdef notdef
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register short delta;
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tcpstat.tcps_rttupdated++;
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tp->t_rttupdated++;
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if (tp->t_srtt != 0) {
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/*
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* srtt is stored as fixed point with 3 bits after the
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* binary point (i.e., scaled by 8). The following magic
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* is equivalent to the smoothing algorithm in rfc793 with
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* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
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* point). Adjust rtt to origin 0.
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*/
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delta = rtt - 1 - (tp->t_srtt >> TCP_RTT_SHIFT);
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if ((tp->t_srtt += delta) <= 0)
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tp->t_srtt = 1;
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/*
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* We accumulate a smoothed rtt variance (actually, a
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* smoothed mean difference), then set the retransmit
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* timer to smoothed rtt + 4 times the smoothed variance.
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* rttvar is stored as fixed point with 2 bits after the
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* binary point (scaled by 4). The following is
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* equivalent to rfc793 smoothing with an alpha of .75
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* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
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* rfc793's wired-in beta.
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*/
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if (delta < 0)
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delta = -delta;
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delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
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if ((tp->t_rttvar += delta) <= 0)
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tp->t_rttvar = 1;
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} else {
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/*
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* No rtt measurement yet - use the unsmoothed rtt.
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* Set the variance to half the rtt (so our first
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* retransmit happens at 3*rtt).
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*/
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tp->t_srtt = rtt << TCP_RTT_SHIFT;
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tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
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}
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#else /* Peterson paper */
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register int delta;
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tcpstat.tcps_rttupdated++;
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@ -1914,7 +1873,6 @@ tcp_xmit_timer(tp, rtt)
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tp->t_srtt = rtt << TCP_RTT_SHIFT;
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tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
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}
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#endif
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tp->t_rtt = 0;
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tp->t_rxtshift = 0;
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@ -1929,13 +1887,8 @@ tcp_xmit_timer(tp, rtt)
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* statistical, we have to test that we don't drop below
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* the minimum feasible timer (which is 2 ticks).
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*/
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#ifdef notdef
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TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
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tp->t_rttmin, TCPTV_REXMTMAX);
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#else /* Peterson */
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TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
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max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
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#endif
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/*
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* We received an ack for a packet that wasn't retransmitted;
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@ -31,7 +31,7 @@
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* SUCH DAMAGE.
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*
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* @(#)tcp_var.h 8.4 (Berkeley) 5/24/95
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* $Id: tcp_var.h,v 1.30 1996/02/27 15:12:53 bde Exp $
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* $Id: tcp_var.h,v 1.31 1996/03/22 18:09:21 wollman Exp $
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*/
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#ifndef _NETINET_TCP_VAR_H_
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@ -191,18 +191,11 @@ struct rmxp_tao {
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* and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
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* binary point, and is smoothed with an ALPHA of 0.75.
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*/
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#ifdef notdef
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#define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
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#define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
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#define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
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#define TCP_RTTVAR_SHIFT 2 /* shift for rttvar; 2 bits */
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#else
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#define TCP_RTT_SCALE 32 /* multiplier for srtt; 3 bits frac. */
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#define TCP_RTT_SHIFT 5 /* shift for srtt; 3 bits frac. */
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#define TCP_RTTVAR_SCALE 16 /* multiplier for rttvar; 2 bits */
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#define TCP_RTTVAR_SHIFT 4 /* shift for rttvar; 2 bits */
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#define TCP_DELTA_SHIFT 2 /* see tcp_input.c */
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#endif
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/*
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* The initial retransmission should happen at rtt + 4 * rttvar.
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@ -214,25 +207,15 @@ struct rmxp_tao {
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* 1.5 tick we need. But, because the bias is
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* statistical, we have to test that we don't drop below
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* the minimum feasible timer (which is 2 ticks).
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#ifdef notdef
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* This macro assumes that the value of TCP_RTTVAR_SCALE
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* is the same as the multiplier for rttvar.
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#else
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* This version of the macro adapted from a paper by Lawrence
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* Brakmo and Larry Peterson which outlines a problem caused
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* by insufficient precision in the original implementation,
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* which results in inappropriately large RTO values for very
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* fast networks.
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#endif
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*/
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#ifdef notdef
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#define TCP_REXMTVAL(tp) \
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(((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
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#else
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#define TCP_REXMTVAL(tp) \
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((((tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT)) \
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+ ((tp)->t_rttvar) >> TCP_RTTVAR_SHIFT))
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#endif
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/* XXX
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* We want to avoid doing m_pullup on incoming packets but that
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