From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751067AbWDQPBj (ORCPT ); Mon, 17 Apr 2006 11:01:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751071AbWDQPBj (ORCPT ); Mon, 17 Apr 2006 11:01:39 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:42395 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S1751065AbWDQPBj (ORCPT ); Mon, 17 Apr 2006 11:01:39 -0400 Subject: Re: irqbalance mandatory on SMP kernels? From: Lee Revell To: "Martin J. Bligh" Cc: "Robert M. Stockmann" , linux-kernel@vger.kernel.org, Randy Dunlap , Linus Torvalds , Andrew Morton , Andre Hedrick , Manfred Spraul , Alan Cox , Kamal Deen In-Reply-To: <4443A6D9.6040706@mbligh.org> References: <4443A6D9.6040706@mbligh.org> Content-Type: text/plain Date: Mon, 17 Apr 2006 11:01:33 -0400 Message-Id: <1145286094.16138.22.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2006-04-17 at 07:31 -0700, Martin J. Bligh wrote: > Robert M. Stockmann wrote: > > Hi, > > > > I noticed that the latest editions of RedHat EL 4.3 and direct > > descendants today need a program called irqbalance to activate > > true SMP IRQ load balancing for your machine's hardware. > > > > If one boots a SMP kernel (2.4.xx or 2.6.xx) kernel on a machine > > which either has 2 or more physical CPU's (also dual-core CPU's) > > , and one does not start up the irqbalance util from the > > kernel-utils package ( see e.g. > > There is an in-kernel IRQ balancer. Redhat just choose to turn it > off, and do it in userspace instead. You can re-enable it if you > compile your own kernel. Round-robin IRQ balancing is inefficient anyway. You'd get better cache utilization letting one CPU take them all. Lee