From owner-freebsd-net Tue Oct 1 13: 7:20 2002 Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9B4C937B401 for ; Tue, 1 Oct 2002 13:07:18 -0700 (PDT) Received: from mx2.nersc.gov (mx2.nersc.gov [128.55.6.22]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1BD5D43E4A for ; Tue, 1 Oct 2002 13:07:18 -0700 (PDT) (envelope-from dart@nersc.gov) Received: from mx2.nersc.gov (localhost [127.0.0.1]) by localhost.nersc.gov (Postfix) with ESMTP id CEBF0593C for ; Tue, 1 Oct 2002 12:44:56 -0700 (PDT) Received: from gemini.nersc.gov (gemini.nersc.gov [128.55.16.111]) by mx2.nersc.gov (Postfix) with ESMTP id 970545936 for ; Tue, 1 Oct 2002 12:44:55 -0700 (PDT) Received: from gemini.nersc.gov (localhost [127.0.0.1]) by gemini.nersc.gov (Postfix) with ESMTP id 552A33B1AE for ; Tue, 1 Oct 2002 12:44:55 -0700 (PDT) X-Mailer: exmh version 2.5 07/13/2001 with nmh-1.0.4 To: net@freebsd.org Subject: limit to data in flight Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1318550241P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Tue, 01 Oct 2002 12:44:55 -0700 From: Eli Dart Message-Id: <20021001194455.552A33B1AE@gemini.nersc.gov> Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org --==_Exmh_1318550241P Content-Type: text/plain; charset=us-ascii Hi all, I'm seeing something strange here... I have a freebsd box running iperf (4.6-RELEASE-p1, iperf 1.6.2 with pthreads patches). When attempting to use a 1MB tcp window, the box won't put more than 256kB in flight after the first connection to a given host. I seem to remember hearing/reading/whatever that freebsd keeps track of congestion stats for a route in the kernel routing table and primes the congestion window for new sockets to the same destination with the previous values (thus eliminating a congestion avoidance cycle on each new socket). High-bandwidth connections between the hosts in question (the other is a linux box of indeterminate recent version) do hit congestion the first time. However, in this particular case (since this is a test machine that we use to diagnose network problems) I'd like to be able to turn it off. I didn't see anything in sysctl that looked obvious, but I'm perfectly willing to believe I missed it. So, can this be turned off? Also, what is the timeout on this data in the kernel? Thanks! --eli ------------------------------------------------------------------------ Eli Dart Office: (510) 495-2999 NERSC Networking and Security Group Cell: (510) 703-4508 Lawrence Berkeley National Laboratory Fax: (510) 486-4316 PGP Key fingerprint = C970 F8D3 CFDD 8FFF 5486 343A 2D31 4478 5F82 B2B3 ------------------------------------------------------------------------ --==_Exmh_1318550241P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (FreeBSD) Comment: This is a comment. iD8DBQE9mfs3LTFEeF+CsrMRApNtAJ91gjpPKcyzAbA3kP/B3rRBxvYYwACeLXPM kzNpTNjLg0sq7MdycvG++Bk= =Oe6o -----END PGP SIGNATURE----- --==_Exmh_1318550241P-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message