From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yinghai Lu Subject: [PATCH 2/2] x86: get more exact nr_irqs Date: Sun, 03 Jan 2010 22:58:21 -0800 Message-ID: <4B41918D.3000605@kernel.org> References: <4B347AEE.6030705@kernel.org> <20091228094707.GH24690@elte.hu> <4B398ECD.1080506@kernel.org> <4807377b1001031906s6b1ee576jc021da2642bb4147@mail.gmail.com> <4B415E73.1050801@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "linux-kernel@vger.kernel.org" , Andrew Morton , NetDEV list , Jesse Brandeburg To: Jesse Brandeburg , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , "Eric W. Biederman" Return-path: Received: from hera.kernel.org ([140.211.167.34]:34169 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752869Ab0ADG7p (ORCPT ); Mon, 4 Jan 2010 01:59:45 -0500 In-Reply-To: <4B415E73.1050801@kernel.org> Sender: netdev-owner@vger.kernel.org List-ID: first check with NR_VECTORS - FIRST_EXTERNAL_VECTOR - 0x20 aka minus exceptions and system vectors. NR_CPUS = 512, and nr_cpu_ids = 128 will have NR_IRQS = 256 + 512 * 64 = 33024 assume we have 20 intel ixgbe 6 port cards (with sriov and ixgbevf) 20 * 6 * 64 * 3 = 23040 first will get: 128 * (256 - 64) = 24576 then with nr_irqs_gsi will get (120 + 8 * 128 + 120 * 256) = 31864 so 24576 will be used for nr_irqs. 24576 * 8 = 196608 bytes will be used for irq_desc_ptrs[] before this patch: have nr_irqs = 120 + 8 * 128 + 120 * 64 = 8824 and irq_desc_ptrs[] is 70592 Signed-off-by: Yinghai Lu --- arch/x86/kernel/apic/io_apic.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) Index: linux-2.6/arch/x86/kernel/apic/io_apic.c =================================================================== --- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c +++ linux-2.6/arch/x86/kernel/apic/io_apic.c @@ -3833,15 +3833,20 @@ int __init arch_probe_nr_irqs(void) { int nr; - if (nr_irqs > (NR_VECTORS * nr_cpu_ids)) - nr_irqs = NR_VECTORS * nr_cpu_ids; + /* 0x20 for ipi etc system vectors */ + nr = NR_VECTORS - FIRST_EXTERNAL_VECTOR - 0x20; + + nr *= nr_cpu_ids; + + if (nr < nr_irqs) + nr_irqs = nr; nr = nr_irqs_gsi + 8 * nr_cpu_ids; #if defined(CONFIG_PCI_MSI) || defined(CONFIG_HT_IRQ) /* * for MSI and HT dyn irq */ - nr += nr_irqs_gsi * 64; + nr += nr_irqs_gsi * 256; #endif if (nr < nr_irqs) nr_irqs = nr;