From owner-freebsd-current@FreeBSD.ORG Sat Mar 3 22:27:29 2007 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 45AAC16A401 for ; Sat, 3 Mar 2007 22:27:29 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (c220-239-3-125.belrs4.nsw.optusnet.com.au [220.239.3.125]) by mx1.freebsd.org (Postfix) with ESMTP id C620913C461 for ; Sat, 3 Mar 2007 22:27:28 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (localhost.vk2pj.dyndns.org [127.0.0.1]) by turion.vk2pj.dyndns.org (8.13.8/8.13.8) with ESMTP id l23MRIMj052479; Sun, 4 Mar 2007 09:27:18 +1100 (EST) (envelope-from peter@turion.vk2pj.dyndns.org) Received: (from peter@localhost) by turion.vk2pj.dyndns.org (8.13.8/8.13.8/Submit) id l23MRInX052478; Sun, 4 Mar 2007 09:27:18 +1100 (EST) (envelope-from peter) Date: Sun, 4 Mar 2007 09:27:18 +1100 From: Peter Jeremy To: Andre Oppermann Message-ID: <20070303222718.GG9421@turion.vk2pj.dyndns.org> References: <17850.13146.266196.499166@grasshopper.cs.duke.edu> <20070303000125.GA9918@turion.vk2pj.dyndns.org> <45E99060.3030404@freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="KuLpqunXa7jZSBt+" Content-Disposition: inline In-Reply-To: <45E99060.3030404@freebsd.org> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.13 (2006-08-11) Cc: freebsd-current@freebsd.org, Andrew Gallatin Subject: Re: excessive TCP duplicate acks? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 03 Mar 2007 22:27:29 -0000 --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 wrote: >Peter Jeremy wrote: >>On 2007-Jan-26 11:59:06 -0500, Andrew Gallatin =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+--