[src/trunk]: src/sys/netinet Fix the bug in the tcp transmit prediction code.

[ragge <ragge%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/373f202e188a
branches:  trunk
changeset: 554018:373f202e188a
user:      ragge <ragge%NetBSD.org@localhost>
date:      Fri Oct 24 10:25:40 2003 +0000

description:
Fix the bug in the tcp transmit prediction code.
During testing the prediction counters show a hit-rate on about 85% for
packets sent on a local LAN, and better than 99% for intercontinental
high-speed bulk traffic (!).

diffstat:

 sys/netinet/tcp_input.c  |  29 ++++++++---------------------
 sys/netinet/tcp_output.c |   7 ++++---
 2 files changed, 12 insertions(+), 24 deletions(-)

diffs (94 lines):

diff -r 8f0e8d2e1e94 -r 373f202e188a sys/netinet/tcp_input.c
--- a/sys/netinet/tcp_input.c   Fri Oct 24 10:25:08 2003 +0000
+++ b/sys/netinet/tcp_input.c   Fri Oct 24 10:25:40 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_input.c,v 1.185 2003/10/23 20:55:08 mycroft Exp $  */
+/*     $NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge Exp $    */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.185 2003/10/23 20:55:08 mycroft Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge Exp $");
 
 #include "opt_inet.h"
 #include "opt_ipsec.h"
@@ -1476,8 +1476,6 @@
                            SEQ_LEQ(th->th_ack, tp->snd_max) &&
                            tp->snd_cwnd >= tp->snd_wnd &&
                            tp->t_dupacks < tcprexmtthresh) {
-                               int slen;
-
                                /*
                                 * this is a pure ack for outstanding data.
                                 */
@@ -1494,14 +1492,10 @@
                                tcpstat.tcps_rcvackbyte += acked;
                                ND6_HINT(tp);
 
-                               slen = tp->t_lastm->m_len;
+                               if (acked > (tp->t_lastoff - tp->t_inoff))
+                                       tp->t_lastm = NULL;
                                sbdrop(&so->so_snd, acked);
-                               if (so->so_snd.sb_cc != 0) {
-                                       tp->t_lastoff -= acked;
-                                       if (tp->t_lastm->m_len < slen)
-                                               tp->t_inoff -= 
-                                                   (slen - tp->t_lastm->m_len);
-                               }
+                               tp->t_lastoff -= acked;
 
                                /*
                                 * We want snd_recover to track snd_una to
@@ -2118,17 +2112,10 @@
                        sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
                        ourfinisacked = 1;
                } else {
-                       int slen;
-
-                       slen = tp->t_lastm->m_len;
+                       if (acked > (tp->t_lastoff - tp->t_inoff))
+                               tp->t_lastm = NULL;
                        sbdrop(&so->so_snd, acked);
-                       tp->snd_wnd -= acked;
-                       if (so->so_snd.sb_cc != 0) {
-                               tp->t_lastoff -= acked;
-                               if (tp->t_lastm->m_len != slen)
-                                       tp->t_inoff -=
-                                           (slen - tp->t_lastm->m_len);
-                       }
+                       tp->t_lastoff -= acked;
                        ourfinisacked = 0;
                }
                sowwakeup(so);
diff -r 8f0e8d2e1e94 -r 373f202e188a sys/netinet/tcp_output.c
--- a/sys/netinet/tcp_output.c  Fri Oct 24 10:25:08 2003 +0000
+++ b/sys/netinet/tcp_output.c  Fri Oct 24 10:25:40 2003 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_output.c,v 1.104 2003/10/24 03:12:53 enami Exp $   */
+/*     $NetBSD: tcp_output.c,v 1.105 2003/10/24 10:25:40 ragge Exp $   */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -138,7 +138,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.104 2003/10/24 03:12:53 enami Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.105 2003/10/24 10:25:40 ragge Exp $");
 
 #include "opt_inet.h"
 #include "opt_ipsec.h"
@@ -451,7 +451,8 @@
         */
        if (
 #ifdef FAST_MBSEARCH
-           off == 0 || (tp->t_lastoff + tp->t_lastlen) != off
+           off == 0 || tp->t_lastm == NULL ||
+               (tp->t_lastoff + tp->t_lastlen) != off
 #else
            1
 #endif