From owner-freebsd-net@FreeBSD.ORG Thu Nov 10 13:24:29 2005 Return-Path: X-Original-To: net@FreeBSD.org 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 0FBB916A420 for ; Thu, 10 Nov 2005 13:24:29 +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 81FB843D48 for ; Thu, 10 Nov 2005 13:24:27 +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 82BC246BDB for ; Thu, 10 Nov 2005 08:24:24 -0500 (EST) Date: Thu, 10 Nov 2005 13:24:24 +0000 (GMT) From: Robert Watson X-X-Sender: robert@fledge.watson.org To: net@FreeBSD.org Message-ID: <20051110132309.A68007@fledge.watson.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: Subject: TCP inflight (was: Re: Poor Samba throughput on 6.0 (fwd)) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Nov 2005 13:24:29 -0000 I've seen a number of reports that TCP inflight data limiting is substantially impacting performance on high bandwidth, low latency networks. Not knowing much about it, I figured I'd post on net@ and see if anyone here is interested in taking a look at some of the reports (they're easy to find in the mailing list archives) and investigating how to fix them. Robert N M Watson ---------- Forwarded message ---------- Date: Thu, 10 Nov 2005 10:31:03 +0000 From: Joao Barros To: Robert Watson Cc: Mike Jakubik , freebsd-performance@freebsd.org, Arkadi Shishlov Subject: Re: Poor Samba throughput on 6.0 On 11/10/05, Robert Watson wrote: > On Wed, 9 Nov 2005, Mike Jakubik wrote: > >> I have done many tests to try to determine the poor performance on my >> systems (FreeBSD-current connected directly to Windows XP via identical >> Intel Pro 1000 cards) and my only conclusion is that Samba on FreeBSD >> when talking to a Windows box is simply fubared. Im willing to bet thats >> not the case on Linux. I can get great speeds (~30MB/s) using ftp >> between the machines, but when i use Samba, i get a maximum of 11MB/s. I >> have tried playing with mtu size, samba options, polling, but there does >> not seem to be any visible bottlenecks, its just simply slow. It would >> be great if someone could get to the bottom of this, its quite >> frustrating. > > There are a number of TCP related configuration frobs on FreeBSD. It > would be quite interesting to know how modifying each of the following > settings affects Samba performance: > > net.inet.tcp.delayed_ack > net.inet.tcp.sack.enable > net.inet.tcp.inflight.enable > > There has been recent evidence that the inflight bandwidth calculation is > having problems generating stable performance at high bandwidth and low > latency, so I might try that one first. > > Robert N M Watson I just tested on my home machine and delayed_ack and sack.enable have little or no effect on the results. inflight.enable on the other hand had a huge impact! With the file cached I've gone from flat 5.5MB/s up to also flat 7.2MB/s It's an improvement but there is still a difference up to those theoretical 12.5MB/s on a 100mbit link -- Joao Barros