Date: Tue, 4 Mar 2014 22:22:50 -0800 From: hiren panchasara <hiren.panchasara@gmail.com> To: Lawrence Stewart <lstewart@freebsd.org> Cc: Andre Oppermann <andre@freebsd.org>, koobs@freebsd.org, "freebsd-net@freebsd.org" <net@freebsd.org> Subject: Re: TCP Initial Window 10 MFC Message-ID: <CALCpEUFMrZiT-=jOgqOu6_5Q7a-vxGnzTYfmOmsg9_Pd1PJRbg@mail.gmail.com> In-Reply-To: <53169C19.5020008@freebsd.org> References: <201307051458.r65EwObo066269@svn.freebsd.org> <520AED2F.4050001@freebsd.org> <520BB3F0.4020506@freebsd.org> <520C4F03.9040601@freebsd.org> <CALCpEUFpcFhTgh1EqNTuEpS%2Bg7F3p-4NOe1dGHRBr3QD3CDttg@mail.gmail.com> <5316413D.7050000@FreeBSD.org> <53169C19.5020008@freebsd.org>
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On Tue, Mar 4, 2014 at 7:38 PM, Lawrence Stewart <lstewart@freebsd.org> wrote:
<skip>
> I lost the battle of wills on this topic and 10.0 shipped with IW10
> enabled by default :(
>
> As for having it configurable, it is a trivial patch which perhaps,
> Hiren, you might be willing to take a stab at? I obviously did not
> manage to carve out the time last year to push forward with the agenda I
> proposed in this thread, but I will get back to it at some point.
Hi Lawrence,
Let's fix it the right way if possible.
Below is a rough/untested quick patch I came up with. Is this how you
were planning to have "nonstandard" sysctl knob designed?
Index: sys/netinet/tcp_input.c
===================================================================
--- sys/netinet/tcp_input.c (revision 260833)
+++ sys/netinet/tcp_input.c (working copy)
@@ -164,6 +164,19 @@
&VNET_NAME(tcp_do_initcwnd10), 0,
"Enable RFC 6928 (Increasing initial CWND to 10)");
+SYSCTL_NODE(_net_inet_tcp, OID_AUTO, nonstandard, CTLFLAG_RW, 0,
+ "Nonstandard TCP extensions");
+
+VNET_DEFINE(int, tcp_nonstandard_allowed) = 0;
+SYSCTL_VNET_INT(_net_inet_tcp_nonstandard, OID_AUTO, allowed, CTLFLAG_RW,
+ &VNET_NAME(tcp_nonstandard_allowed), 0,
+ "Allow nonstandard TCP extensions");
+
+VNET_DEFINE(int, tcp_nonstandard_initcwnd) = 0;
+SYSCTL_VNET_INT(_net_inet_tcp_nonstandard, OID_AUTO, initcwnd, CTLFLAG_RW,
+ &VNET_NAME(tcp_nonstandard_initcwnd), 0,
+ "Slow-start flight size (initial congestion window)");
+
VNET_DEFINE(int, tcp_do_rfc3465) = 1;
SYSCTL_VNET_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW,
&VNET_NAME(tcp_do_rfc3465), 0,
@@ -368,6 +381,8 @@
*/
if (tp->snd_cwnd == 1)
tp->snd_cwnd = tp->t_maxseg; /* SYN(-ACK) lost */
+ else if (V_tcp_nonstandard_allowed && V_tcp_nonstandard_initcwnd)
+ tp->snd_cwnd = V_tcp_nonstandard_initcwnd * tp->t_maxseg;
else if (V_tcp_do_initcwnd10)
tp->snd_cwnd = min(10 * tp->t_maxseg,
max(2 * tp->t_maxseg, 14600));
Index: sys/netinet/tcp_var.h
===================================================================
--- sys/netinet/tcp_var.h (revision 260833)
+++ sys/netinet/tcp_var.h (working copy)
@@ -610,6 +610,7 @@
VNET_DECLARE(int, tcp_delack_enabled);
VNET_DECLARE(int, tcp_do_rfc3390);
VNET_DECLARE(int, tcp_do_initcwnd10);
+VNET_DECLARE(int, tcp_nonstandard_allowed);
+VNET_DECLARE(int, tcp_nonstandard_initcwnd);
VNET_DECLARE(int, tcp_sendspace);
VNET_DECLARE(int, tcp_recvspace);
VNET_DECLARE(int, path_mtu_discovery);
@@ -622,6 +623,7 @@
#define V_tcp_delack_enabled VNET(tcp_delack_enabled)
#define V_tcp_do_rfc3390 VNET(tcp_do_rfc3390)
#define V_tcp_do_initcwnd10 VNET(tcp_do_initcwnd10)
+#define V_tcp_nonstandard_allowed VNET(tcp_nonstandard_allowed)
+#define V_tcp_nonstandard_initcwnd VNET(tcp_nonstandard_initcwnd)
#define V_tcp_sendspace VNET(tcp_sendspace)
#define V_tcp_recvspace VNET(tcp_recvspace)
#define V_path_mtu_discovery VNET(path_mtu_discovery)
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