From owner-freebsd-net@FreeBSD.ORG Mon Sep 7 11:40:17 2009 Return-Path: Delivered-To: net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 32232106566C for ; Mon, 7 Sep 2009 11:40:17 +0000 (UTC) (envelope-from wjw@digiware.nl) Received: from mail.digiware.nl (unknown [IPv6:2001:4cb8:1:106::2]) by mx1.freebsd.org (Postfix) with ESMTP id C1DEC8FC14 for ; Mon, 7 Sep 2009 11:40:16 +0000 (UTC) Received: from localhost (localhost.digiware.nl [127.0.0.1]) by mail.digiware.nl (Postfix) with ESMTP id 5F3EE153437; Mon, 7 Sep 2009 13:40:15 +0200 (CEST) X-Virus-Scanned: amavisd-new at digiware.nl Received: from mail.digiware.nl ([127.0.0.1]) by localhost (rack1.digiware.nl [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BYOK8QbMBQ05; Mon, 7 Sep 2009 13:40:13 +0200 (CEST) Received: from [212.61.27.67] (opteron [212.61.27.67]) by mail.digiware.nl (Postfix) with ESMTP id 49197153436; Mon, 7 Sep 2009 13:40:13 +0200 (CEST) Message-ID: <4AA4F11C.4060200@digiware.nl> Date: Mon, 07 Sep 2009 13:40:12 +0200 From: Willem Jan Withagen Organization: Digiware User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Manish Vachharajani References: <4AA14018.3010102@digiware.nl> <5bc218350909041002x670460c8nf202a714182d1bf6@mail.gmail.com> In-Reply-To: <5bc218350909041002x670460c8nf202a714182d1bf6@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: net@freebsd.org Subject: Re: UDP output performance 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: Mon, 07 Sep 2009 11:40:17 -0000 Manish Vachharajani wrote: > Hmm, what version of FreeBSD are you using? I don't know the solution > but I wonder if it is related to a similar problem we are having with > TCP connection scaling, both under 7.2 and 8.0 over a 10 Gb link. > We've been trying to track it down, and if you see it for UDP as well > that may give some clues. > > If you do a netstat -idh what is the output? Does the recieving > interface show any Ierrs or drops? If so, you should be able to do a > sysctl dev.em..stats=1 and then see some output via > dmesg. Does this show any missed packets? > > Oh, also, what kind of machine are you running on? Well this turns out to be a pilot error, in that I created such a complex bandwidth evaluation that on buffer full the packet got tossed in the application. :( Just stripping that out, and just do a try send while(not send) { usleep(1 packet-time); try again; } Reduced my packet loss to < 0.1% and I'm able to squeeze a nice > 900 Mbit/s out of a single em(4) port. Still no packets begin dropped in netstat -i. So now I'm off hunting for 'bugs' in snmp, cacti, mrtg to see why they don't like the counters. Even when I'm using the 64bit counters I get really spiky bandwidth results. Equal to those when using 32 bits counters, so certainly things are not as I think they are. Other thing is to see how Lin* is performing on this test. So trying to install ubuntu 9.04. --WjW