From owner-freebsd-net Fri Nov 1 12:32:37 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 657FB37B401 for ; Fri, 1 Nov 2002 12:32:36 -0800 (PST) Received: from tp.databus.com (p70-227.acedsl.com [66.114.70.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id C3D3A43E75 for ; Fri, 1 Nov 2002 12:32:35 -0800 (PST) (envelope-from barney@tp.databus.com) Received: from tp.databus.com (localhost.databus.com [127.0.0.1]) by tp.databus.com (8.12.6/8.12.6) with ESMTP id gA1KWSCA092476; Fri, 1 Nov 2002 15:32:28 -0500 (EST) (envelope-from barney@tp.databus.com) Received: (from barney@localhost) by tp.databus.com (8.12.6/8.12.6/Submit) id gA1KWS7Y092475; Fri, 1 Nov 2002 15:32:28 -0500 (EST) Date: Fri, 1 Nov 2002 15:32:28 -0500 From: Barney Wolff To: Mark Allman Cc: freebsd-net@freebsd.org Subject: Re: Problem in High Speed and Long Delay with FreeBSD Message-ID: <20021101203228.GA92397@tp.databus.com> References: <3DC2D147.8357C198@lmco.com> <200211011928.OAA63524@guns.lerc.nasa.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200211011928.OAA63524@guns.lerc.nasa.gov> User-Agent: Mutt/1.4i X-Scanned-By: MIMEDefang 2.21 (www . roaringpenguin . com / mimedefang) 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 Try retrieving a very large file via ftp. The sendfile() code seems more efficient than ttcp, and if performance improves that may be a clue that the problem lies in the user/kernel interface. If not, probably in the stack. Could it conceivably be a resonance effect between the actual rtt and the stack timing granularity? I would also try setting ttcp's block size to a multiple of the exact transmitted seg size rather than a power of 2. Barney -- Barney Wolff http://www.databus.com/bwresume.pdf I'm available by contract or FT, in the NYC metro area or via the 'Net. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message