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Date:      Tue, 18 Jan 2000 15:29:43 +0100 (CET)
From:      Luigi Rizzo <luigi@info.iet.unipi.it>
To:        Luigi Rizzo <luigi@info.iet.unipi.it>
Cc:        net@freebsd.org
Subject:   Re: Feature: net.inet.tcp.local_slowstart ?
Message-ID:  <200001181429.PAA59352@info.iet.unipi.it>
In-Reply-To: <200001181429.PAA59342@info.iet.unipi.it> from Luigi Rizzo at "Jan 18, 2000 03:29:01 pm"

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> Hi,
> may i add a new sysctl variable,
> 
> 	net.inet.tcp.local_slowstart
> 
> to control whether or not to do slowstart on local connections ?
> FreeBSD now blasts a whole window at the beginning of a connection
> when the remote party is on the same subnet.
> This at times might cause problems. The above variable would
> leave current behaviour unchanged if left to 0 (default), and
> do the regular slowstart if set to 1
> 
> Would go to -current after the release i suppose.

forgot to add that the patch is minimal:

--- src/sys/netinet/tcp_input.c Thu Oct 14 13:49:38 1999
+++ /sys/netinet/tcp_input.c    Mon Jan 17 15:33:49 2000
@@ -89,6 +89,11 @@
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW,
        &tcp_delack_enabled, 0, "");

+static int local_slowstart=1;
+SYSCTL_INT(_net_inet_tcp, OID_AUTO, local_slowstart, CTLFLAG_RW,
+       &local_slowstart, 0,
+       "Do slowstart even on local networks");
+
 #ifdef TCP_DROP_SYNFIN
 static int drop_synfin = 0;
 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
@@ -2228,7 +2233,7 @@
        /*
         * Don't force slow-start on local network.
         */
-       if (!in_localaddr(inp->inp_faddr))
+       if (local_slowstart || !in_localaddr(inp->inp_faddr))
                tp->snd_cwnd = mss;

        if (rt->rt_rmx.rmx_ssthresh) {

	cheers
	luigi
> 	cheers
> 	luigi
> 
> 



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