From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262033AbULHFxD (ORCPT ); Wed, 8 Dec 2004 00:53:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262034AbULHFxD (ORCPT ); Wed, 8 Dec 2004 00:53:03 -0500 Received: from willy.net1.nerim.net ([62.212.114.60]:32010 "EHLO willy.net1.nerim.net") by vger.kernel.org with ESMTP id S262033AbULHFxA (ORCPT ); Wed, 8 Dec 2004 00:53:00 -0500 Date: Wed, 8 Dec 2004 06:39:53 +0100 From: Willy Tarreau To: Karsten Desler Cc: P@draigBrady.com, "David S. Miller" , netdev@oss.sgi.com, linux-kernel@vger.kernel.org Subject: Re: _High_ CPU usage while routing (mostly) small UDP packets Message-ID: <20041208053953.GC17946@alpha.home.local> References: <20041206205305.GA11970@soohrt.org> <20041206134849.498bfc93.davem@davemloft.net> <20041206224107.GA8529@soohrt.org> <41B58A58.8010007@draigBrady.com> <20041207112139.GA3610@soohrt.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041207112139.GA3610@soohrt.org> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 07, 2004 at 12:21:39PM +0100, Karsten Desler wrote: > > I also notice that a lot of time is spent allocating > > and freeing the packet buffers (and possible hidden > > time due to cache misses due to allocating on one > > CPU and freeing on another?). > > How many [RT]xDescriptors do you have configured by the way? > > 256. I increased them to 1024 shortly after the profiling run, but > didn't notice any change in the cpu usage (will try again with cyclesoak). Have you checked the interrupts rate ? I had an e1000 eating many CPU cycles because it would generate 50000 interrupts/s. Passing the module InterruptThrottleRate=5000 definitely calmed it down, and more than doubled the data rate. Regards Willy