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Commit 0fa0ebbf authored by Mike Travis's avatar Mike Travis Committed by Ingo Molnar
Browse files

irq: allocate irq_desc_ptrs array based on nr_irqs 



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: default avatarMike Travis <travis@sgi.com>
parent e2f4d065

kernel/irq/handle.c

+9 −2
Original line number Diff line number Diff line
@@ -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)

kernel/irq/internals.h

+7 −0
Original line number Diff line number Diff line
@@ -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);