From owner-freebsd-stable@FreeBSD.ORG Fri Feb 17 11:15:06 2006 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 3B5AF16A420 for ; Fri, 17 Feb 2006 11:15:06 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from cyrus.watson.org (cyrus.watson.org [209.31.154.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id E29A743D80 for ; Fri, 17 Feb 2006 11:15:05 +0000 (GMT) (envelope-from rwatson@FreeBSD.org) Received: from fledge.watson.org (fledge.watson.org [209.31.154.41]) by cyrus.watson.org (Postfix) with ESMTP id 54A4546B39; Fri, 17 Feb 2006 06:14:51 -0500 (EST) Date: Fri, 17 Feb 2006 11:18:26 +0000 (GMT) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: Oliver Brandmueller In-Reply-To: <20060216121604.GE55530@e-Gitt.NET> Message-ID: <20060217111729.F37321@fledge.watson.org> References: <6.2.3.4.0.20060215221957.076524f8@64.7.153.2> <20060216100359.GA10327@jbell.maths.tcd.ie> <20060216121604.GE55530@e-Gitt.NET> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-stable@freebsd.org Subject: Re: tcp throughput and net.inet.tcp.inflight.enable X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Feb 2006 11:15:06 -0000 On Thu, 16 Feb 2006, Oliver Brandmueller wrote: > On Thu, Feb 16, 2006 at 10:03:59AM +0000, David Malone wrote: >> I think in a situation where your network is fast and large amounts >> of buffering do not imply high latency, then the inflight limiting >> stuff probably isn't useful. >> >> (I have some coworkers who reckon that inflight limiting can do the wrong >> thing in other situations too, but they haven't had a chance to investigate >> their suspicions yet.) > > Maybe it's an idea to make this an per-interface value. On my local GigE NFS > network it might not be useful (well, maybe even lowering the performance), > while on another interface with lots of connects from all over the world > does a good job. > > Dunno, it's probably not so easy to implement this, then. Andre recently committed a change to CVS HEAD to disable inflight limiting when the RTT is very small, as it runs into problems with clock resolution and scaling of predicted bandwidth. I assume this will be merged to RELENG_6 in the near future. Robert N M Watson