Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753758Ab3FJXRg (ORCPT ); Mon, 10 Jun 2013 19:17:36 -0400 Received: from mail-ie0-f177.google.com ([209.85.223.177]:37366 "EHLO mail-ie0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752148Ab3FJXRe (ORCPT ); Mon, 10 Jun 2013 19:17:34 -0400 MIME-Version: 1.0 In-Reply-To: <20130609145457.GA2245@breakpoint.cc> References: <1370644273-10495-1-git-send-email-yinghai@kernel.org> <1370644273-10495-3-git-send-email-yinghai@kernel.org> <20130609145457.GA2245@breakpoint.cc> Date: Mon, 10 Jun 2013 16:17:33 -0700 X-Google-Sender-Auth: Ii1pDUSECyc8ZbwNDlHCjedbru8 Message-ID: Subject: Re: [PATCH v3 02/27] x86, irq: Modify irq chip once for irq remapping From: Yinghai Lu To: Sebastian Andrzej Siewior Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Bjorn Helgaas , "Rafael J. Wysocki" , "linux-pci@vger.kernel.org" , Linux Kernel Mailing List , Konrad Rzeszutek Wilk , Joerg Roedel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4826 Lines: 157 On Sun, Jun 9, 2013 at 7:54 AM, Sebastian Andrzej Siewior wrote: > On Fri, Jun 07, 2013 at 03:30:48PM -0700, Yinghai Lu wrote: >> Current code: after irq remapping is enabled, irq_chip fields are modified >> during every irq setup. >> mp_register_gsi >> io_apic_set_pci_routing >> io_apic_setup_irq_pin >> setup_ioapic_irq >> ioapic_register_intr >> setup_remapped_irq >> native_setup_msi_irqs >> setup_msi_irq >> setup_remapped_irq >> default_setup_hpet_msi >> setup_remapped_irq >> that is not efficient. >> >> We only need to modify those irq chip one time just after we enable >> irq mapping. > > The overhead you talk about is calling setup_remapped_irq() for every > interrupt from the mp_register_gsi() call chain? MSI & HPET should happen only > once, or do I miss something? yes, and for every pci_enable_msi per pci device. > >> Change irq_remap_modify_chip_defaults() to __init as it only gets >> called during booting stage, via irq_remap_modify_chips(). >> >> Affected irq_chip: ioapic_chip, msi_chip, hpet_msi_type. >> We don't need to use #ifdef in irq_remap_modify_chips(): >> IRQ_REMAP only support x86_64 and X86_IO_APIC and PCI_MSI. >> HPET_TIMER is set when x86_64 is set. >> When we have IRQ_REMAP enabled, al three chips are defined and >> used. > > all, not al > > Still, the user could disable hpet or apic from the commandline but this > should cause any harm as the irq chips shouldn't be used then. should "not" ? > >> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c >> index 904611b..ff50b90 100644 >> --- a/arch/x86/kernel/apic/apic.c >> +++ b/arch/x86/kernel/apic/apic.c >> @@ -1552,6 +1552,8 @@ void enable_x2apic(void) >> int __init enable_IR(void) >> { >> #ifdef CONFIG_IRQ_REMAP >> + int ret; >> + >> if (!irq_remapping_supported()) { >> pr_debug("intr-remapping not supported\n"); >> return -1; >> @@ -1563,7 +1565,12 @@ int __init enable_IR(void) >> return -1; >> } >> >> - return irq_remapping_enable(); >> + ret = irq_remapping_enable(); >> + >> + if (ret >= 0) >> + irq_remap_modify_chips(); > > This looks like ehm, well not well. > Could you please change this to: > ret = irq_remapping_enable(); > if (ret) > return ret; > > irq_remap_modify_chips(); > >> + >> + return ret; So you want to use ret = irq_remapping_enable(); if (ret < 0) return ret; irq_remap_modify_chips(); return ret; instead of: ret = irq_remapping_enable(); if (ret >= 0) irq_remap_modify_chips(); return ret; >> #endif >> return -1; >> } >> diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c >> index 07ce86a..21ef344 100644 >> --- a/drivers/iommu/irq_remapping.c >> +++ b/drivers/iommu/irq_remapping.c >> @@ -373,19 +373,26 @@ static void ir_print_prefix(struct irq_data *data, struct seq_file *p) >> seq_printf(p, " IR-%s", data->chip->name); >> } >> >> -static void irq_remap_modify_chip_defaults(struct irq_chip *chip) >> +static void __init irq_remap_modify_chip_defaults(struct irq_chip *chip) >> { >> + printk(KERN_DEBUG "irq_chip: %s ==> IR-%s", chip->name, chip->name); > > If you need this please use pr_debug and add a \n at the end. No, I hate pr_debug, as it is useless unless have DEBUG defined. later even ask user to append "debug ignore_loglevel", we still get nothing unless user recompile the kernel. will add "\n", not sure how that get dropped. > >> chip->irq_print_chip = ir_print_prefix; >> chip->irq_ack = ir_ack_apic_edge; >> chip->irq_eoi = ir_ack_apic_level; >> chip->irq_set_affinity = x86_io_apic_ops.set_affinity; >> } >> >> +void __init irq_remap_modify_chips(void) >> +{ >> + irq_remap_modify_chip_defaults(&ioapic_chip); >> + irq_remap_modify_chip_defaults(&msi_chip); >> + irq_remap_modify_chip_defaults(&hpet_msi_type); >> +} >> + >> bool setup_remapped_irq(int irq, struct irq_cfg *cfg, struct irq_chip *chip) >> { >> if (!irq_remapped(cfg)) >> return false; >> irq_set_status_flags(irq, IRQ_MOVE_PCNTXT); >> - irq_remap_modify_chip_defaults(chip); > > chip is not required, and can be removed. yes. Thanks Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/