From owner-freebsd-hackers@FreeBSD.ORG Sat Feb 28 18:19:26 2004 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 4AC2B16A4CE for ; Sat, 28 Feb 2004 18:19:26 -0800 (PST) Received: from mail.sandvine.com (sandvine.com [199.243.201.138]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9EF7043D2D for ; Sat, 28 Feb 2004 18:19:25 -0800 (PST) (envelope-from don@sandvine.com) Received: by mail.sandvine.com with Internet Mail Service (5.5.2657.72) id <15P457C1>; Sat, 28 Feb 2004 21:19:24 -0500 Message-ID: From: Don Bowman To: 'Deepak Jain' , freebsd-hackers@freebsd.org Date: Sat, 28 Feb 2004 21:19:18 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2657.72) Content-Type: text/plain; charset="iso-8859-1" Subject: RE: em0, polling performance, P4 2.8ghz FSB 800mhz 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: Sun, 29 Feb 2004 02:19:26 -0000 > I have a machine running 4.9. P4 2.8Ghz, 800mhz bus, Intel PRO/1000 > ethernet connected to a Cisco, both sides are locked to 1000/FD. > > The kernel has HZ=1000, and DEVICE_POLLING, IPFW, DUMMYNET, > etc. After > only a few minutes of run time under an attack ~90,000 pps. > The attack > has been limited at the router to JUST incoming TCP port 80 inbound > traffic. I don't know why the machine is having such a hard > time under > the load. The cpu shows it is >90% idle even under the worst of the > attack. What am I doing wrong? I think there's a problem with CPU time not getting properly accounted for in device polling, so it may be busier than you think. For this scenario, i would set net.inet.tcp.blackhole=2. You might be spending a lot of time creating the ICMP unreachable messages, rather than in the network driver (where device polling would help). --don