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?
> 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.
> 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;
> #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.
> 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.
> return true;
> }
Sebastian
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