From owner-freebsd-net@FreeBSD.ORG Mon Jul 7 08:47:25 2008 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B14521065687 for ; Mon, 7 Jul 2008 08:47:25 +0000 (UTC) (envelope-from andre@freebsd.org) Received: from c00l3r.networx.ch (c00l3r.networx.ch [62.48.2.2]) by mx1.freebsd.org (Postfix) with ESMTP id C97188FC15 for ; Mon, 7 Jul 2008 08:47:24 +0000 (UTC) (envelope-from andre@freebsd.org) Received: (qmail 29125 invoked from network); 7 Jul 2008 07:37:53 -0000 Received: from localhost (HELO [127.0.0.1]) ([127.0.0.1]) (envelope-sender ) by c00l3r.networx.ch (qmail-ldap-1.03) with SMTP for ; 7 Jul 2008 07:37:53 -0000 Message-ID: <4871D81B.8070507@freebsd.org> Date: Mon, 07 Jul 2008 10:47:23 +0200 From: Andre Oppermann User-Agent: Thunderbird 1.5.0.14 (Windows/20071210) MIME-Version: 1.0 To: Robert Watson References: <4867420D.7090406@gtcomm.net> <4869B025.9080006@gtcomm.net><486A7E45.3030902@gtcomm.net> <486A8F24.5010000@gtcomm.net><486A9A0E.6060308@elischer.org> <486B41D5.3060609@gtcomm.net><486B4F11.6040906@gtcomm.net><486BC7F5.5070604@gtcomm.net><20080703160540.W6369@delplex.bde.org><486C7F93.7010308@gtcomm.net><20080703195521.O6973@delplex.bde.org><486D35A0.4000302@gtcomm.net><486DF1A3.9000409@gtcomm.net><486E65E6.3060301@gtcomm.net> <2d3001c8def1$f4309b90$020b000a@bartwrkstxp> <486FFF70.3090402@gtcomm.net> <20080706132148.E44832@fledge.watson.org> In-Reply-To: <20080706132148.E44832@fledge.watson.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: FreeBSD Net , Bart Van Kerckhove , Ingo Flaschberger , Paul Subject: Re: Freebsd IP Forwarding performance (question, and some info) [7-stable, current, em, smp] 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 Jul 2008 08:47:25 -0000 Robert Watson wrote: > Experience suggests that forwarding workloads see significant lock > contention in the routing and transmit queue code. The former needs > some kernel hacking to address in order to improve parallelism for > routing lookups. The latter is harder to address given the hardware > you're using: modern 10gbps cards frequently offer multiple transmit > queues that can be used independently (which our cxgb driver supports), > but 1gbps cards generally don't. Actually the routing code is not contended. The workload in router is mostly serialized without much opportunity for contention. With many interfaces and any-to-any traffic patterns it may get some contention. The locking overhead per packet is always there and has some impact though. -- Andre