From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753909Ab0BMMEV (ORCPT ); Sat, 13 Feb 2010 07:04:21 -0500 Received: from out02.mta.xmission.com ([166.70.13.232]:42035 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752416Ab0BMMEU (ORCPT ); Sat, 13 Feb 2010 07:04:20 -0500 To: Yinghai Lu Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andrew Morton , Suresh Siddha , linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , Rusty Russell 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> <4B7676BB.8030608@kernel.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Sat, 13 Feb 2010 04:04:10 -0800 In-Reply-To: <4B7676BB.8030608@kernel.org> (Yinghai Lu's message of "Sat\, 13 Feb 2010 01\:54\:03 -0800") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in02.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in02.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yinghai Lu writes: > On 02/12/2010 07:44 PM, Eric W. Biederman wrote: >> Yinghai Lu writes: >> >>> ---------spareirq radix tree related ---------------- >>> 94007e8: irq: remove not need bootmem code >>> 4b0d3fa: radix: move radix init early >>> 56af1a9: sparseirq: change irq_desc_ptrs to static >>> b236235: sparseirq: use radix_tree instead of ptrs array >>> 5918787: x86: remove arch_probe_nr_irqs >>> >>> so could reduce nr_irqs limitation for bunch ixgbe... >>> >>> ---------------x86 logical flat related ----------- >>> f5954c4: use nr_cpus= to set nr_cpu_ids early >>> 7b8d6a9: x86: use num_processors for possible cpus >>> d79d1de: x86: make 32bit apic flat to physflat switch like 64bit >> >> Thanks for keeping this work alive. >> >> 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. >> > > please check > > Subject: [PATCH] x86: use vector_desc instead of vector_irq > > Eric pointed out that radix tree version of irq_to_desc will magnify delay on the path > of handle_irq. > use vector_desc to reduce the calling of irq_to_desc. > > next step: need to change all ack, mask, umask, eoi for all irq_chip to take irq_desc > > Signed-off-by: Yinghai Lu > > #ifdef CONFIG_X86_LOCAL_APIC > Index: linux-2.6/arch/x86/lguest/boot.c > =================================================================== > --- linux-2.6.orig/arch/x86/lguest/boot.c > +++ linux-2.6/arch/x86/lguest/boot.c > @@ -819,7 +819,7 @@ static void __init lguest_init_IRQ(void) > > for (i = FIRST_EXTERNAL_VECTOR; i < NR_VECTORS; i++) { > /* Some systems map "vectors" to interrupts weirdly. Not us! */ > - __get_cpu_var(vector_irq)[i] = i - FIRST_EXTERNAL_VECTOR; > + __get_cpu_var(vector_desc)[i] = irq_to_desc(i - FIRST_EXTERNAL_VECTOR); > if (i != SYSCALL_VECTOR) > set_intr_gate(i, interrupt[i - FIRST_EXTERNAL_VECTOR]); > } YH It appears that irq_to_desc_alloc_node has not been called yet so the setting of vector_desc needs to move to lguest_setup_irq. Eric