net.inet.tcp.tso=1 still neceesary with fxp was Re: TCP differences in 7.2 vs 7.1

[Pyun YongHyeon]

On Fri, May 22, 2009 at 03:50:07PM -0400, Michael L. Squires wrote:
> 
> 
> On Thu, 21 May 2009, Pyun YongHyeon wrote:
> 
> >On Wed, May 20, 2009 at 05:55:29PM -0400, Michael L. Squires wrote:
> >>I started having speed problems after shifting from 7.1-STABLE to
> >>7.1-PRERELEASE.  They have continued with 7.2-STABLLE.
> >>
> >>Reverting to the 7.1-STABLE kernel eliminated the problem.
> >>
> >>After downloading 7.2-STABLE from cvsup.freebsd.org at about 10:40 AM EST
> >>on 5/20/2009, doing a buildworld/buildkernel/installkernel/installworld
> >>cycle I still need to execute "net.inet.tcp.tso=1" to elminate throughput
> >>problems between my home system (on Comcast) and my office PC (connected
> >>via a Time-Warner connection).  This also affects connections to other
> >>systems; downloading Web pages (ebay.com) speeds up after I change the TSO
> >>entry.
> >>
> >>The box in question runs NAT and has an fxp (Intel Pro100) interface
> >>connected to a Comcast cable modem and an em (Intel Pro1000) interface
> >>connected to the internal network.
> >>
> >>There are no network errors in "netstat -i" on either interface.
> >>
> >>The "if_fxp.c" code appears to be the May 7 version.
> >>
> >
> >You should have cvs rev. 1.266.2.15 of if_fxp.c.
> >
> >>This is the dmesg entry for the card in question.  The system is a dual 
> >>Xeon
> >>Supermicro 1U box, 1GB RAM, single 300GB IDE hard drive.
> >>
> >>fxp0: <Intel 82551 Pro/100 Ethernet> port 0xe400-0xe43f mem
> >>0xfebfd000-0xfebfdfff,0xfeb80000-0xfeb9ffff irq 27 at device 7.0 on pci0
> >>miibus0: <MII bus> on fxp0
> >>
> >
> >Since you use both em(4) and fxp(4) I'd like to know which driver
> >has the issue. Instead of disabling TSO of network stack try
> >disabling TSO for each interface. For instance,
> >1. Diable TSO of em(4) and check you see the same issue
> >   (ifconfig em0 -tso).
> >2. Diable TSO of fxp(4) and check you see the same issue
> >   (ifconfig fxp0 -tso).
> >
> 
> The version of if_fpx.c is in fact 1.266.2.15.
> 
> Connecting to the FreeBSD box from a PC with a bash shell under XP 
> SP3/Cygwin OpenSSH I find
> 
> (1)  disable "tso" on the internal "em0" interface has no effect; but
> 
> (2)  disabling "tso" on the external "fxp0" inteface eliminates the 
> througput problem.  The effect appears to be the same as using sysctl to 
> disable tso on all interfaces.
> 
> With "tso" enabled on the "fxp0" interface the connection (reading email 
> using "pine" in a large window) hung completely.
> 
> There are no errors in "netstat -i" nor in /var/log/messages.
> 
> "netstat -e" on the XP PC shows no discards or errors; however, I don't
> think I've ever seen a PC under Windows admit to network errors.
> 
> The fxp0 interface connects to a Comcast cable modem, which eventually 
> connects to my office PC which is in the "iga.in.gov" domain hosted by 
> TimeWarner.
> 
> I'll be happy to run anything else you want.
> 

Would you capture the failing TCP session with tcpdump and mail me
the URL of the captured file(off-list)?