Date: Sun, 4 Mar 2007 09:27:18 +1100 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-current@freebsd.org, Andrew Gallatin <gallatin@cs.duke.edu> Subject: Re: excessive TCP duplicate acks? Message-ID: <20070303222718.GG9421@turion.vk2pj.dyndns.org> In-Reply-To: <45E99060.3030404@freebsd.org> References: <17850.13146.266196.499166@grasshopper.cs.duke.edu> <20070303000125.GA9918@turion.vk2pj.dyndns.org> <45E99060.3030404@freebsd.org>
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--KuLpqunXa7jZSBt+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2007-Mar-03 16:12:32 +0100, Andre Oppermann <andre@freebsd.org> wrote: >Peter Jeremy wrote: >>On 2007-Jan-26 11:59:06 -0500, Andrew Gallatin <gallatin@cs.duke.edu>=20 >>wrote: >> >>>When running some benchmarks, I noticed tons of duplicate acks showing >>>up in systat -tcp (thousands, or tens of thousands per second). >> >>Whilst investigating other problems, I've just seen the same on 6.2. =2E.. >This thing is really strange and difficult to debug. At least for me, it's not readily reproducable. I've written a perl script to try and locate the problem in tcpdumps I've taken for other reasons and haven't seen any recurrences of it. >I haven't experienced this bug myself which makes it even harder to debug. It's not something you'd probably notice unless you were specifically looking. In my case, I only noticed because I am trying to track an ipfilter bug and that connection setup had been flagged so I was studying the tcpdump output. Any ideas on where to add some checks to try and detect this without needing to pour over tcpdump traces? --=20 Peter Jeremy --KuLpqunXa7jZSBt+ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFF6fZG/opHv/APuIcRAv9uAJ99c8/9uJN1wOvfPUUb42xslaEspgCdFIUT fTDe3FVCSBD0zKTer1u3VtY= =2Ajz -----END PGP SIGNATURE----- --KuLpqunXa7jZSBt+--
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