From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756898Ab0BMDvU (ORCPT ); Fri, 12 Feb 2010 22:51:20 -0500 Received: from terminus.zytor.com ([198.137.202.10]:42270 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755807Ab0BMDvT (ORCPT ); Fri, 12 Feb 2010 22:51:19 -0500 Message-ID: <4B762137.4050604@zytor.com> Date: Fri, 12 Feb 2010 19:49:11 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc11 Thunderbird/3.0.1 MIME-Version: 1.0 To: "Eric W. Biederman" CC: Yinghai Lu , Ingo Molnar , Thomas Gleixner , Andrew Morton , Suresh Siddha , linux-kernel@vger.kernel.org, Jeremy Fitzhardinge Subject: Re: [PATCH 0/8] tip related: radix tree for spareseirq and logical flat clean up References: <1266029390-30907-1-git-send-email-yinghai@kernel.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/12/2010 07:44 PM, Eric W. Biederman wrote: > > Thanks for keeping this work alive. > Indeed. I am hoping to put this in tip tomorrow or so. > I just skimmed through do_IRQ and I happened to notice that > we have an unnecessary inefficiency that using a radix tree for > irq_to_desc will magnify. > > handle_irq should take an struct irq_desc * instead of a unsigned int irq. > > and the per cpu vector_irq array should become a per cpu vector_desc array. > > As soon as irq_to_desc is more than &irq_desc[irq] this saves us work > and cache line misses at the cost of a simple code cleanup. Good catch. I haven't looked through the details yet, but I presume this can be done on top of this changeset? -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.