lkml.org 
[lkml]   [2009]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] x86: arch_probe_nr_irqs
Yinghai Lu wrote:
> Impact: save RAM with large NR_CPUS, get smaller nr_irqs
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>

Built and tested on an 8-core intel system. Great reduction
in NR_IRQS:

[ 0.000000] NR_IRQS:33024 nr_irqs:320
Thanks Yinghai!

Ingo - shall I push this one as well? (If not, then you
can add my:

Acked-by: Mike Travis <travis@sgi.com>

Thanks,
Mike

>
> ---
> arch/x86/include/asm/irq_vectors.h | 7 ++-----
> arch/x86/kernel/io_apic.c | 16 ++++++++++++++++
> include/linux/interrupt.h | 1 +
> kernel/irq/handle.c | 9 ++-------
> kernel/softirq.c | 5 +++++
> 5 files changed, 26 insertions(+), 12 deletions(-)
>
> Index: linux-2.6/arch/x86/include/asm/irq_vectors.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/irq_vectors.h
> +++ linux-2.6/arch/x86/include/asm/irq_vectors.h
> @@ -120,14 +120,11 @@
> # endif
> #else
>
> -/* defined as a macro so nr_irqs = max_nr_irqs(nr_cpu_ids) can be used */
> -# define max_nr_irqs(nr_cpus) \
> - ((8 * nr_cpus) > (32 * MAX_IO_APICS) ? \
> +# define NR_IRQS \
> + ((8 * NR_CPUS) > (32 * MAX_IO_APICS) ? \
> (NR_VECTORS + (8 * NR_CPUS)) : \
> (NR_VECTORS + (32 * MAX_IO_APICS))) \
>
> -# define NR_IRQS max_nr_irqs(NR_CPUS)
> -
> #endif
>
> #elif defined(CONFIG_X86_VOYAGER)
> Index: linux-2.6/arch/x86/kernel/io_apic.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/io_apic.c
> +++ linux-2.6/arch/x86/kernel/io_apic.c
> @@ -3851,6 +3851,22 @@ void __init probe_nr_irqs_gsi(void)
> nr_irqs_gsi = nr;
> }
>
> +#ifdef CONFIG_SPARSE_IRQ
> +int __init arch_probe_nr_irqs(void)
> +{
> + int nr;
> +
> + nr = ((8 * nr_cpu_ids) > (32 * nr_ioapics) ?
> + (NR_VECTORS + (8 * nr_cpu_ids)) :
> + (NR_VECTORS + (32 * nr_ioapics)));
> +
> + if (nr < nr_irqs && nr > nr_irqs_gsi)
> + nr_irqs = nr;
> +
> + return 0;
> +}
> +#endif
> +
> /* --------------------------------------------------------------------------
> ACPI-based IOAPIC Configuration
> -------------------------------------------------------------------------- */
> Index: linux-2.6/include/linux/interrupt.h
> ===================================================================
> --- linux-2.6.orig/include/linux/interrupt.h
> +++ linux-2.6/include/linux/interrupt.h
> @@ -481,6 +481,7 @@ int show_interrupts(struct seq_file *p,
> struct irq_desc;
>
> extern int early_irq_init(void);
> +extern int arch_probe_nr_irqs(void);
> extern int arch_early_irq_init(void);
> extern int arch_init_chip_data(struct irq_desc *desc, int cpu);
>
> Index: linux-2.6/kernel/irq/handle.c
> ===================================================================
> --- linux-2.6.orig/kernel/irq/handle.c
> +++ linux-2.6/kernel/irq/handle.c
> @@ -59,10 +59,6 @@ EXPORT_SYMBOL_GPL(nr_irqs);
>
> #ifdef CONFIG_SPARSE_IRQ
>
> -#ifndef max_nr_irqs
> -#define max_nr_irqs(nr_cpus) NR_IRQS
> -#endif
> -
> static struct irq_desc irq_desc_init = {
> .irq = -1,
> .status = IRQ_DISABLED,
> @@ -137,9 +133,8 @@ int __init early_irq_init(void)
> int legacy_count;
> int i;
>
> - /* initialize nr_irqs based on nr_cpu_ids */
> - nr_irqs = max_nr_irqs(nr_cpu_ids);
> -
> + /* initialize nr_irqs based on nr_cpu_ids */
> + arch_probe_nr_irqs();
> printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d\n", NR_IRQS, nr_irqs);
>
> desc = irq_desc_legacy;
> Index: linux-2.6/kernel/softirq.c
> ===================================================================
> --- linux-2.6.orig/kernel/softirq.c
> +++ linux-2.6/kernel/softirq.c
> @@ -806,6 +806,11 @@ int __init __weak early_irq_init(void)
> return 0;
> }
>
> +int __init __weak arch_probe_nr_irqs(void)
> +{
> + return 0;
> +}
> +
> int __init __weak arch_early_irq_init(void)
> {
> return 0;



\
 
 \ /
  Last update: 2009-01-13 00:09    [from the cache]
©2003-2011 Jasper Spaans