From owner-freebsd-net@FreeBSD.ORG Fri Jan 14 08:39:40 2011 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 1E190106564A for ; Fri, 14 Jan 2011 08:39:40 +0000 (UTC) (envelope-from sthaug@nethelp.no) Received: from bizet.nethelp.no (bizet.nethelp.no [195.1.209.33]) by mx1.freebsd.org (Postfix) with SMTP id 54E018FC19 for ; Fri, 14 Jan 2011 08:39:38 +0000 (UTC) Received: (qmail 91561 invoked from network); 14 Jan 2011 08:39:36 -0000 Received: from bizet.nethelp.no (HELO localhost) (195.1.209.33) by bizet.nethelp.no with SMTP; 14 Jan 2011 08:39:36 -0000 Date: Fri, 14 Jan 2011 09:39:36 +0100 (CET) Message-Id: <20110114.093936.74681829.sthaug@nethelp.no> To: cswiger@mac.com From: sthaug@nethelp.no In-Reply-To: <54D25D8E-ED8C-41E8-BD14-4EB86F4D63C3@mac.com> References: <0B45B324-A819-4230-BBE3-F8468F2DA88F@mac.com> <20110114154326.E27511@besplex.bde.org> <54D25D8E-ED8C-41E8-BD14-4EB86F4D63C3@mac.com> X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: freebsd-net@freebsd.org Subject: Re: igb watchdog timeouts 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: Fri, 14 Jan 2011 08:39:40 -0000 > > They have enough buffers (128 for each of tx and rx IIRC). The only thing > > polling mode gave for them was lower latency, but this cost enabling > > polling in the idle loop, which wastes 100% of at least 1 CPU and some > > power. Without polling in idle, polling gives very high latency (even > > worse than low-quality interrupt moderation does). > > Sure-- there are circumstances where a machine would always have traffic to process, for which idle polling was beneficial to enable. I have a couple of servers with Broadcom (bge) GigE interfaces. These servers became completely unresponsive/unusable at high network traffic (presumably due to the interrupt processing) but were able to handle the same traffic with no problems after switching to polling. This was in the 7.0 timeframe. I still have the same servers/interfaces running with polling, but now at 7.3. Steinar Haug, Nethelp consulting, sthaug@nethelp.no