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irq: allocate irq_desc_ptrs array based on nr_irqs

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Impact: allocate irq_desc_ptrs in preparation for making it variable-sized.

This addresses this memory usage bump when NR_CPUS bumped from 128 to 4096:

    34816   +229376    264192  +658%  irq_desc_ptrs(.data.read_mostly)

The patch is split into two parts, the first simply allocates the
irq_desc_ptrs array.  Then next will deal with making it variable.
This is only when CONFIG_SPARSE_IRQS=y.

Signed-off-by: Mike Travis <travis@sgi.com>
This commit is contained in:
Mike Travis 2009-01-10 22:24:06 -08:00 committed by Ingo Molnar
parent e2f4d06545
commit 0fa0ebbf15
2 changed files with 16 additions and 2 deletions
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11
kernel/irq/handle.c
View file

@ -17,6 +17,7 @@
#include <linux/kernel_stat.h>
#include <linux/rculist.h>
#include <linux/hash.h>
#include <linux/bootmem.h>
#include "internals.h"
@ -110,7 +111,7 @@ static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
*/
DEFINE_SPINLOCK(sparse_irq_lock);
struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;
struct irq_desc **irq_desc_ptrs __read_mostly;
static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS_LEGACY-1] = {
@ -137,6 +138,9 @@ int __init early_irq_init(void)
desc = irq_desc_legacy;
legacy_count = ARRAY_SIZE(irq_desc_legacy);
/* allocate irq_desc_ptrs array based on nr_irqs */
irq_desc_ptrs = alloc_bootmem(nr_irqs * sizeof(void *));
for (i = 0; i < legacy_count; i++) {
desc[i].irq = i;
desc[i].kstat_irqs = kstat_irqs_legacy[i];
@ -153,7 +157,10 @@ int __init early_irq_init(void)
struct irq_desc *irq_to_desc(unsigned int irq)
{
return (irq < nr_irqs) ? irq_desc_ptrs[irq] : NULL;
if (irq_desc_ptrs && irq < nr_irqs)
return irq_desc_ptrs[irq];
return NULL;
}
struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)

7
kernel/irq/internals.h
View file

@ -16,7 +16,14 @@ extern int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
extern struct lock_class_key irq_desc_lock_class;
extern void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr);
extern spinlock_t sparse_irq_lock;
#ifdef CONFIG_SPARSE_IRQ
/* irq_desc_ptrs allocated at boot time */
extern struct irq_desc **irq_desc_ptrs;
#else
/* irq_desc_ptrs is a fixed size array */
extern struct irq_desc *irq_desc_ptrs[NR_IRQS];
#endif
#ifdef CONFIG_PROC_FS
extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);