From owner-freebsd-hackers@FreeBSD.ORG Tue May 30 20:02:30 2006 Return-Path: X-Original-To: hackers@freebsd.org Delivered-To: freebsd-hackers@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 60E5316A770 for ; Tue, 30 May 2006 20:02:30 +0000 (UTC) (envelope-from mwm-keyword-freebsdhackers2.e313df@mired.org) Received: from mired.org (vpn.mired.org [66.92.153.74]) by mx1.FreeBSD.org (Postfix) with SMTP id 9BB4543D55 for ; Tue, 30 May 2006 20:02:29 +0000 (GMT) (envelope-from mwm-keyword-freebsdhackers2.e313df@mired.org) Received: (qmail 96806 invoked by uid 1001); 30 May 2006 20:02:28 -0000 Received: by bhuda.mired.org (tmda-sendmail, from uid 1001); Tue, 30 May 2006 16:02:28 -0400 (EDT) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17532.42196.508218.964130@bhuda.mired.org> Date: Tue, 30 May 2006 16:02:28 -0400 To: hackers@freebsd.org X-Mailer: VM 7.17 under 21.4 (patch 19) "Constant Variable" XEmacs Lucid X-Primary-Address: mwm@mired.org X-face: "5Mnwy%?j>IIV\)A=):rjWL~NB2aH[}Yq8Z=u~vJ`"(,&SiLvbbz2W`; h9L,Yg`+vb1>RG% *h+%X^n0EZd>TM8_IB;a8F?(Fb"lw'IgCoyM.[Lg#r\ From: Mike Meyer X-Delivery-Agent: TMDA/1.0.3 (Seattle Slew) Cc: Subject: Asymmetric ethernet throughput? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 May 2006 20:02:36 -0000 I was doing some network testing, and noticed something odd: The network throughput was asymmetric. I was sending between 2 and 5 times as much data as I was receiving. Swapping the ends of the test didn't change that. Changing the non-FBSD box for a FBSD box made the throughput symmetric. Details: One end is always a FreeBSD 5.5 box with a RealTek 8138 nic. Testing is done with netstrain, built from ports. I first saw this with an OSX 10.4.6 box, a G4 powerbook. The FreeBSD box was sending ~10MB/sec on a 100BaseT network, which I regard as excellent. But I was only receiving 3M/sec. I tried swapping the server and client ends of netstrain, and got the same results: I was sending 10MB/sec to OSX, and receiving about 3MB/sec from it. I then tried making the other end a FBSD 6.1-RELEASE box, and the throughput was symmetric, with both ends sending and receiving 10MB/sec. I rebooted the 6.1 box into Ubuntu lunix running a 2.6.12 kernel. Again, I got asymmetric results - but this time it was the other way: I was receving ~10MB/sec, but only sending about 3MB/sec. Trying this between the Linux box and the OSX box (sorry, I've only got one of each) gave me symmetric ~10MB/sec throughput. I'm just curious if there's an explanation for this. Thanks, http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information.