[src/trunk]: src/sys/netinet Limit the tcp initial window setting to 10, leav...

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

details:   https://anonhg.NetBSD.org/src/rev/0c6938c2f11f
branches:  trunk
changeset: 785994:0c6938c2f11f
user:      christos <christos%NetBSD.org@localhost>
date:      Wed Apr 10 00:16:03 2013 +0000

description:
Limit the tcp initial window setting to 10, leaving it by default to 4
and simplifying the code in process. Per draft-ietf-initcwnd-08.txt.

diffstat:

 sys/netinet/tcp_subr.c   |  23 ++++++++++++++++++++---
 sys/netinet/tcp_usrreq.c |  29 +++++++++++++++++++++++++----
 sys/netinet/tcp_var.h    |   6 +++---
 3 files changed, 48 insertions(+), 10 deletions(-)

diffs (139 lines):

diff -r e63910d2426d -r 0c6938c2f11f sys/netinet/tcp_subr.c
--- a/sys/netinet/tcp_subr.c    Tue Apr 09 16:39:19 2013 +0000
+++ b/sys/netinet/tcp_subr.c    Wed Apr 10 00:16:03 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_subr.c,v 1.248 2012/09/08 02:58:13 msaitoh Exp $   */
+/*     $NetBSD: tcp_subr.c,v 1.249 2013/04/10 00:16:03 christos Exp $  */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -91,7 +91,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_subr.c,v 1.248 2012/09/08 02:58:13 msaitoh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_subr.c,v 1.249 2013/04/10 00:16:03 christos Exp $");
 
 #include "opt_inet.h"
 #include "opt_ipsec.h"
@@ -173,11 +173,28 @@
 int    tcp_ack_on_push = 0;    /* set to enable immediate ACK-on-PUSH */
 int    tcp_do_ecn = 0;         /* Explicit Congestion Notification */
 #ifndef TCP_INIT_WIN
-#define        TCP_INIT_WIN    0       /* initial slow start window */
+#define        TCP_INIT_WIN    4       /* initial slow start window */
 #endif
 #ifndef TCP_INIT_WIN_LOCAL
 #define        TCP_INIT_WIN_LOCAL 4    /* initial slow start window for local nets */
 #endif
+/*
+ * Up to 5 we scale linearly, to reach 3 * 1460; then (iw) * 1460.
+ * This is to simulate current behavior for iw == 4
+ */
+int tcp_init_win_max[] = {
+        1 * 1460,
+        1 * 1460,
+        2 * 1460,
+        2 * 1460,
+        3 * 1460,
+        5 * 1460,
+        6 * 1460,
+        7 * 1460,
+        8 * 1460,
+        9 * 1460,
+       10 * 1460
+};
 int    tcp_init_win = TCP_INIT_WIN;
 int    tcp_init_win_local = TCP_INIT_WIN_LOCAL;
 int    tcp_mss_ifmtu = 0;
diff -r e63910d2426d -r 0c6938c2f11f sys/netinet/tcp_usrreq.c
--- a/sys/netinet/tcp_usrreq.c  Tue Apr 09 16:39:19 2013 +0000
+++ b/sys/netinet/tcp_usrreq.c  Wed Apr 10 00:16:03 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_usrreq.c,v 1.165 2012/06/02 21:36:47 dsl Exp $     */
+/*     $NetBSD: tcp_usrreq.c,v 1.166 2013/04/10 00:16:03 christos Exp $        */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -95,7 +95,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: tcp_usrreq.c,v 1.165 2012/06/02 21:36:47 dsl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: tcp_usrreq.c,v 1.166 2013/04/10 00:16:03 christos Exp $");
 
 #include "opt_inet.h"
 #include "opt_ipsec.h"
@@ -1600,6 +1600,27 @@
 }
 
 static int
+sysctl_tcp_init_win(SYSCTLFN_ARGS)
+{
+       int error;
+       u_int iw;
+       struct sysctlnode node;
+
+       iw = *(u_int *)rnode->sysctl_data;
+       node = *rnode;
+       node.sysctl_data = &iw;
+       node.sysctl_size = sizeof(iw);
+       error = sysctl_lookup(SYSCTLFN_CALL(&node));
+       if (error || newp == NULL)
+               return error;
+
+       if (iw >= __arraycount(tcp_init_win_max))
+               return EINVAL;
+       *(u_int *)rnode->sysctl_data = iw;
+       return 0;
+}
+
+static int
 sysctl_tcp_keep(SYSCTLFN_ARGS)
 {  
        int error;
@@ -1732,7 +1753,7 @@
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "init_win",
                       SYSCTL_DESCR("Initial TCP congestion window"),
-                      NULL, 0, &tcp_init_win, 0,
+                      sysctl_tcp_init_win, 0, &tcp_init_win, 0,
                       CTL_NET, pf, IPPROTO_TCP, TCPCTL_INIT_WIN, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
@@ -1861,7 +1882,7 @@
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "init_win_local",
                       SYSCTL_DESCR("Initial TCP window size (in segments)"),
-                      NULL, 0, &tcp_init_win_local, 0,
+                      sysctl_tcp_init_win, 0, &tcp_init_win_local, 0,
                       CTL_NET, pf, IPPROTO_TCP, TCPCTL_INIT_WIN_LOCAL,
                       CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
diff -r e63910d2426d -r 0c6938c2f11f sys/netinet/tcp_var.h
--- a/sys/netinet/tcp_var.h     Tue Apr 09 16:39:19 2013 +0000
+++ b/sys/netinet/tcp_var.h     Wed Apr 10 00:16:03 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tcp_var.h,v 1.169 2012/02/02 19:43:08 tls Exp $        */
+/*     $NetBSD: tcp_var.h,v 1.170 2013/04/10 00:16:04 christos Exp $   */
 
 /*
  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@@ -613,8 +613,7 @@
  * Compute the initial window for slow start.
  */
 #define        TCP_INITIAL_WINDOW(iw, segsz) \
-       (((iw) == 0) ? (min(4 * (segsz), max(2 * (segsz), 4380))) : \
-        ((segsz) * (iw)))
+       min((iw) * (segsz), max(2 * (segsz), tcp_init_win_max[(iw)]))
 
 /*
  * TCP statistics.
@@ -797,6 +796,7 @@
 extern  int tcp_msl;           /* max segment life */
 extern int tcp_init_win;       /* initial window */
 extern int tcp_init_win_local; /* initial window for local nets */
+extern int tcp_init_win_max[11];/* max sizes for values of tcp_init_win_* */
 extern int tcp_mss_ifmtu;      /* take MSS from interface, not in_maxmtu */
 extern int tcp_compat_42;      /* work around ancient broken TCP peers */
 extern int tcp_cwm;            /* enable Congestion Window Monitoring */