From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arjan van de Ven Subject: Re: [RFC] irqbalance: Mark in-kernel irqbalance as obsolete, set to N by default Date: Fri, 04 Aug 2006 07:36:06 -0700 Message-ID: <44D35B56.6060500@linux.intel.com> References: <44CE3F5E.4010305@intel.com> <20060803194550.9ff31bc1.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Auke Kok , linux-kernel@vger.kernel.org, jesse.brandeburg@intel.com, john.ronciak@intel.com, netdev@vger.kernel.org Return-path: Received: from mga06.intel.com ([134.134.136.21]:61836 "EHLO orsmga101.jf.intel.com") by vger.kernel.org with ESMTP id S932489AbWHDO7N (ORCPT ); Fri, 4 Aug 2006 10:59:13 -0400 To: Andrew Morton In-Reply-To: <20060803194550.9ff31bc1.akpm@osdl.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Andrew Morton wrote: > On Mon, 31 Jul 2006 10:35:26 -0700 > Auke Kok wrote: > >> We've recently seen a number of user bug reports against e1000 that the >> in-kernel irqbalance code is detrimental to network latency. The algorithm >> keeps swapping irq's for NICs from cpu to cpu causing extremely high network >> latency (>1000ms). > > What kernel versions? Some IRQ balancer fixes went in shortly after 2.6.17. > > It would be better if poss to fix the balancer rather than deprecating it. to some degree the in kernel balancer cannot really make the level of decisions that a userspace balancer can make, at least not without making all kernel developers vomit ;) (for example the userspace balancer looks in /proc/interrupts and parses that to see which interrupts are used by networking versus which by storage etc, and has different balancing policies for those and other classes; the networking policy basically comes down to "pin the interrupt unless some higher networking interrupt really gets in the way")