From owner-cvs-all@FreeBSD.ORG Wed Aug 1 08:38:03 2007 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 98A3116A41A; Wed, 1 Aug 2007 08:38:03 +0000 (UTC) (envelope-from peterjeremy@optushome.com.au) Received: from turion.vk2pj.dyndns.org (c220-239-20-82.belrs4.nsw.optusnet.com.au [220.239.20.82]) by mx1.freebsd.org (Postfix) with ESMTP id 082EB13C480; Wed, 1 Aug 2007 08:38:02 +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 (8.14.1/8.14.1) with ESMTP id l718c1AW001636; Wed, 1 Aug 2007 18:38:01 +1000 (EST) (envelope-from peter@turion.vk2pj.dyndns.org) Received: (from peter@localhost) by turion.vk2pj.dyndns.org (8.14.1/8.14.1/Submit) id l718c1Zo001635; Wed, 1 Aug 2007 18:38:01 +1000 (EST) (envelope-from peter) Date: Wed, 1 Aug 2007 18:38:01 +1000 From: Peter Jeremy To: Peter Wemm Message-ID: <20070801083801.GI1152@turion.vk2pj.dyndns.org> References: <200707312211.l6VMBupO010347@repoman.freebsd.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="45Z9DzgjV8m4Oswq" Content-Disposition: inline In-Reply-To: <200707312211.l6VMBupO010347@repoman.freebsd.org> X-PGP-Key: http://members.optusnet.com.au/peterjeremy/pubkey.asc User-Agent: Mutt/1.5.16 (2007-06-09) Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/netinet tcp_subr.c tcp_timer.h X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Aug 2007 08:38:03 -0000 --45Z9DzgjV8m4Oswq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2007-Jul-31 22:11:56 +0000, Peter Wemm wrote: > To demonstrate, boot with kern.hz=3D100. ssh to a box on local ethernet > and establish a reliable round-trip-time (ie: type a few commands). > Then unplug the ethernet and press a key. Time how long it takes to > drop the connection. I've bumped into this problem as well but chose a slightly different solution. I've left the TCPTV_MIN/tcp_rexmit_min code alone (because I believed the bit about it being scaled to hz). Instead I added a new sysctl "Minimum Retransmission Period before Dropping Connection" and require that a connection's t_rxtshift remain at TCP_MAXRXTSHIFT until that time has expired. My gut feeling is that putting an artifical lower bound on the RTT is a hackish way to control the retransmit timeout - I thought the TCP algorithms relied on knowing the real RTT to correctly handle retransmissions. A variable that explicitly controls the retransmit timeout would seem easier to understand. I thought I'd PR'd the patch but it looks like I haven't. If anyone is interested, I'll submit it. --=20 Peter Jeremy --45Z9DzgjV8m4Oswq Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (FreeBSD) iD8DBQFGsEZp/opHv/APuIcRAgKQAJ0dKeCye/rmjTcrRro2Y+R+U5sd9QCfb/xH +r97Lu7+2eE7Vcub9vM3Xd8= =qFMq -----END PGP SIGNATURE----- --45Z9DzgjV8m4Oswq--