From owner-freebsd-current@FreeBSD.ORG Sat Mar 3 00:01:59 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 1E0D716A40A for ; Sat, 3 Mar 2007 00:01:59 +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 3231E13C481 for ; Sat, 3 Mar 2007 00:01:37 +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 l2301QW0009984; Sat, 3 Mar 2007 11:01:26 +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 l2301P9j009983; Sat, 3 Mar 2007 11:01:25 +1100 (EST) (envelope-from peter) Date: Sat, 3 Mar 2007 11:01:25 +1100 From: Peter Jeremy To: Andrew Gallatin Message-ID: <20070303000125.GA9918@turion.vk2pj.dyndns.org> References: <17850.13146.266196.499166@grasshopper.cs.duke.edu> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="u3/rZRmxL6MmkK24" Content-Disposition: inline In-Reply-To: <17850.13146.266196.499166@grasshopper.cs.duke.edu> 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 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 00:01:59 -0000 --u3/rZRmxL6MmkK24 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2007-Jan-26 11:59:06 -0500, Andrew Gallatin 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. The following trace was taken on 192.168.234.1, which is running 6.2-RELEASE/i386 (with ipfilter enabled) with fxp (Intel 82559) NICs. 192.168.234.64 is running 6.2-STABLE/amd64 from late January (no firewall active) with a bge (Broadcom BCM5705 A3, ASIC rev. 0x3003) NIC and checksum offloading enabled. The multiple SYN packets are due to a bug in the IPfilter state management, though it eventually allows a SYN through. (And it is not totally unrealistic for multiple SYNs to be required before a SYN-ACK is received so this does not excuse the ACK flood). Note that the duplicate ACKs are being sent from the host without a firewall so this does not appear to be related to ipfilter (or kern/102653). The common factor seems to be amd64. 08:11:59.725733 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:02.722826 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:05.922699 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:09.122652 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:12.322614 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:15.522575 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:21.722501 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:33.922361 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:58.122057 IP 192.168.234.64.49195 > 192.168.234.1.22: S 3976363428:39= 76363428(0) win 65535 08:12:58.122596 IP 192.168.234.1.22 > 192.168.234.64.49195: S 3756522873:37= 56522873(0) ack 3976363429 win 65535 08:12:58.122775 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652287= 4 win 65535 08:12:58.274044 IP 192.168.234.1.22 > 192.168.234.64.49195: P 3756522874:37= 56522913(39) ack 3976363429 win 65535 08:12:58.274285 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274347 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274393 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274434 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274478 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274521 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274562 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274607 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274645 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274688 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274727 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274766 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274801 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274835 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274873 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274907 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274941 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.274975 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275010 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275044 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275120 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275163 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275200 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275243 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275282 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275317 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275352 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275387 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275421 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275455 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275490 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275525 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275559 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275594 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275629 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275663 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275697 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275732 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275766 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.275801 IP 192.168.234.64.49195 > 192.168.234.1.22: P 3976363429:39= 76363468(39) ack 3756522913 win 65535 08:12:58.275838 IP 192.168.234.64.49195 > 192.168.234.1.22: P 3976363468:39= 76364220(752) ack 3756522913 win 65535 08:12:58.279466 IP 192.168.234.1.22 > 192.168.234.64.49195: . ack 397636422= 0 win 64909 08:12:58.279671 IP 192.168.234.64.49195 > 192.168.234.1.22: . ack 375652291= 3 win 65535 08:12:58.301824 IP 192.168.234.1.22 > 192.168.234.64.49195: P 3756522913:37= 56523657(744) ack 3976364220 win 64948 08:12:58.302362 IP 192.168.234.64.49195 > 192.168.234.1.22: P 3976364220:39= 76364244(24) ack 3756523657 win 65535 08:12:58.402330 IP 192.168.234.1.22 > 192.168.234.64.49195: . ack 397636424= 4 win 65535 --=20 Peter Jeremy --u3/rZRmxL6MmkK24 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFF6LrV/opHv/APuIcRAoi2AJ47i+gca062Rc3XTZE0vgRG9M9HAACfdE3R z9z4BKbdp22GZ5WkFiyRZQw= =lQLy -----END PGP SIGNATURE----- --u3/rZRmxL6MmkK24--