From owner-freebsd-hackers@FreeBSD.ORG Thu Apr 10 14:58:08 2003 Return-Path: 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 0F96137B401; Thu, 10 Apr 2003 14:58:08 -0700 (PDT) Received: from mother.ludd.luth.se (mother.ludd.luth.se [130.240.16.3]) by mx1.FreeBSD.org (Postfix) with ESMTP id F26AF43FBD; Thu, 10 Apr 2003 14:58:05 -0700 (PDT) (envelope-from pantzer@ludd.luth.se) Received: from ludd.luth.se (skalman.campus.luth.se [130.240.197.52]) by mother.ludd.luth.se (8.11.6+Sun/8.9.3) with ESMTP id h3ALw1810603; Thu, 10 Apr 2003 23:58:02 +0200 (MEST) Message-ID: <3E95E8E9.3080102@ludd.luth.se> Date: Thu, 10 Apr 2003 23:58:01 +0200 From: Mattias Pantzare User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.2.1) Gecko/20030217 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Terry Lambert References: <20030410171640.C44793B2@porter.dc.luth.se> <3E95E446.73B7E510@mindspring.com> In-Reply-To: <3E95E446.73B7E510@mindspring.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: freebsd-hackers@freebsd.org cc: freebsd-performance@freebsd.org cc: "Jin Guojun \[DSD\]" cc: Eric Anderson cc: David Gilbert Subject: Re: tcp_output starving -- is due to mbuf get delay? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Apr 2003 21:58:08 -0000 > >>What happens in that case for me is that I run out of CPU resources. Try >>running "top" in one window and "netstat 1" in another while bashing the >>net with ttcp. > > > This is incredibly bizarre. It's very hard to saturate the CPU > at only 1Gbit: in all cases, you are I/O bound, not CPU bound, > and not memory bandwidth bound > >>IMPORTANT NOTE: Several tests here has shown that this is VERY BADLY >>affected if You have too much LAN equipment (especially VLAN seems to be >>harmful) at the edges. My speed of 960 Mbit/sec fell to 165 just by adding >>10 feet of cable and two switches :-( > > > The products that Jeffrey Hsu and I and Alfred and Jon Mini > worked on at a previous company had no problems at all on a > 1Gbit/S saturating the link, even through a VLAN trunk through > Cisco and one other less intelligent switch (i.e. two switches > and a VLAN trunk). A key factor here is that the testst where on a link with a 20ms round-tip time, and using a singel TCP connection. So the switches where in addition to a few routers on a 10Gbit/s network.