Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761050AbYAaARg (ORCPT ); Wed, 30 Jan 2008 19:17:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756073AbYAaARZ (ORCPT ); Wed, 30 Jan 2008 19:17:25 -0500 Received: from wx-out-0506.google.com ([66.249.82.234]:17976 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755997AbYAaARY (ORCPT ); Wed, 30 Jan 2008 19:17:24 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=GDfnRCMU2ooB3ioR17AcG00wuiOZfqz5Ou7UJhRQ2ZpmDWoIBZVLTyjGg3ZKylKjXG1D/4emhZfFNMJVwQD8Dc2W/sVEdf4+rByonaYvS/5EVhys79KaYfFRCr6nRWHOVNFH2LLNSQO+be9BMlXN91FZQUWDtfKFZrt+DIciLXc= Message-ID: <649aecc70801301617m6331bcb8i8ce60366e182c739@mail.gmail.com> Date: Wed, 30 Jan 2008 19:17:20 -0500 From: "SANGTAE HA" To: "Bruce Allen" Subject: Re: e1000 full-duplex TCP performance well below wire speed Cc: "Linux Kernel Mailing List" , netdev@vger.kernel.org, "Stephen Hemminger" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080130.055333.192844925.davem@davemloft.net> <20080130082136.1017631d@deepthought> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1606 Lines: 34 Hi Bruce, On Jan 30, 2008 5:25 PM, Bruce Allen wrote: > > In our application (cluster computing) we use a very tightly coupled > high-speed low-latency network. There is no 'wide area traffic'. So it's > hard for me to understand why any networking components or software layers > should take more than milliseconds to ramp up or back off in speed. > Perhaps we should be asking for a TCP congestion avoidance algorithm which > is designed for a data center environment where there are very few hops > and typical packet delivery times are tens or hundreds of microseconds. > It's very different than delivering data thousands of km across a WAN. > If your network latency is low, regardless of type of protocols should give you more than 900Mbps. I can guess the RTT of two machines is less than 4ms in your case and I remember the throughputs of all high-speed protocols (including tcp-reno) were more than 900Mbps with 4ms RTT. So, my question which kernel version did you use with your broadcomm NIC and got more than 900Mbps? I have two machines connected by a gig switch and I can see what happens in my environment. Could you post what parameters did you use for netperf testing? and also if you set any parameters for your testing, please post them here so that I can see that happens to me as well. Regards, Sangtae -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/