Date: Fri, 16 Nov 2007 01:00:44 +0100 From: Andre Oppermann <andre@freebsd.org> To: Gregory Wright <gwright@antiope.com> Cc: freebsd-current@freebsd.org Subject: Re: excessive TCP dulplicate acks revisted Message-ID: <473CDDAC.9020503@freebsd.org> In-Reply-To: <17995F62-7E9B-42E3-A7FA-30143C704C34@antiope.com> References: <46B41421-3112-40C6-84D9-094FA771F93E@antiope.com> <4735CE3A.7020905@freebsd.org> <C621C4E4-4230-4658-B668-A0612B632565@antiope.com> <473780DB.2040705@freebsd.org> <17995F62-7E9B-42E3-A7FA-30143C704C34@antiope.com>
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Gregory Wright wrote: > > On Nov 11, 2007, at 5:23 PM, Andre Oppermann wrote: > >> Gregory Wright wrote: >>> On Nov 10, 2007, at 10:28 AM, Andre Oppermann wrote: >>>> >>> Hi Andre, >>> I also took a look at the bge (4) driver in 7.0-BETA2. As far as I >>> can tell, >>> it does not support TSO (there is no ioctl supporting TSO enable/disable >>> as there is for the em(4) driver). >> >>> Might the chip --- a BCM5704_B0 --- not be completely initialized? This >>> might explain why the machine with the BCM5714_B3 chips works, while >>> the other machine shows the duplicate ACK bug. >> >> Perhaps. Do you see the duplicate ACKs in a tcpdump on both the sender >> and the receiver? If you see it on the sender too, then it must be a >> bug in our network stack or the driver (by requeuing the same packet >> over and over again). >> >> --Andre > > The logs show that the duplicate ACKs are generated only by the > receiver. I suspect a bug in the driver, perhaps the ACK packet > is not being removed from the TX buffer ring. Examining the transmitted > packets should be enough to rule out a network stack problem. Is > there any debugging infrastructure I can use or do I just have to > hack in on my own? We don't have an infrastructure to deal with this kind of driver problems. You have to instrument the driver code to report stuck mbufs. -- Andre
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