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sparse irq_desc[] array: core kernel and x86 changes

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Impact: new feature

Problem on distro kernels: irq_desc[NR_IRQS] takes megabytes of RAM with
NR_CPUS set to large values. The goal is to be able to scale up to much
larger NR_IRQS value without impacting the (important) common case.

To solve this, we generalize irq_desc[NR_IRQS] to an (optional) array of
irq_desc pointers.

When CONFIG_SPARSE_IRQ=y is used, we use kzalloc_node to get irq_desc,
this also makes the IRQ descriptors NUMA-local (to the site that calls
request_irq()).

This gets rid of the irq_cfg[] static array on x86 as well: irq_cfg now
uses desc->chip_data for x86 to store irq_cfg.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Yinghai Lu 2008-12-05 18:58:31 -08:00 • committed by Ingo Molnar
parent 218d11a8b0
commit 0b8f1efad3
23 changed files with 659 additions and 173 deletions
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54
include/linux/irq.h
View file

@ -129,6 +129,8 @@ struct irq_chip {
const char *typename;
};
struct timer_rand_state;
struct irq_2_iommu;
/**
* struct irq_desc - interrupt descriptor
* @irq: interrupt number for this descriptor
@ -154,6 +156,13 @@ struct irq_chip {
*/
struct irq_desc {
unsigned int irq;
#ifdef CONFIG_SPARSE_IRQ
struct timer_rand_state *timer_rand_state;
unsigned int *kstat_irqs;
# ifdef CONFIG_INTR_REMAP
struct irq_2_iommu *irq_2_iommu;
# endif
#endif
irq_flow_handler_t handle_irq;
struct irq_chip *chip;
struct msi_desc *msi_desc;
@ -181,13 +190,51 @@ struct irq_desc {
const char *name;
} ____cacheline_internodealigned_in_smp;
extern void early_irq_init(void);
extern void arch_early_irq_init(void);
extern void arch_init_chip_data(struct irq_desc *desc, int cpu);
extern void arch_init_copy_chip_data(struct irq_desc *old_desc,
struct irq_desc *desc, int cpu);
extern void arch_free_chip_data(struct irq_desc *old_desc, struct irq_desc *desc);
#ifndef CONFIG_SPARSE_IRQ
extern struct irq_desc irq_desc[NR_IRQS];
static inline struct irq_desc *irq_to_desc(unsigned int irq)
{
return (irq < nr_irqs) ? irq_desc + irq : NULL;
return (irq < NR_IRQS) ? irq_desc + irq : NULL;
}
static inline struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
{
return irq_to_desc(irq);
}
#ifdef CONFIG_GENERIC_HARDIRQS
# define for_each_irq_desc(irq, desc) \
for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc++)
# define for_each_irq_desc_reverse(irq, desc) \
for (irq = nr_irqs - 1, desc = irq_desc + (nr_irqs - 1); \
irq >= 0; irq--, desc--)
#endif
#else
extern struct irq_desc *irq_to_desc(unsigned int irq);
extern struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu);
extern struct irq_desc *move_irq_desc(struct irq_desc *old_desc, int cpu);
# define for_each_irq_desc(irq, desc) \
for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs; irq++, desc = irq_to_desc(irq))
# define for_each_irq_desc_reverse(irq, desc) \
for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0; irq--, desc = irq_to_desc(irq))
#define kstat_irqs_this_cpu(DESC) \
((DESC)->kstat_irqs[smp_processor_id()])
#define kstat_incr_irqs_this_cpu(irqno, DESC) \
((DESC)->kstat_irqs[smp_processor_id()]++)
#endif
/*
* Migration helpers for obsolete names, they will go away:
@ -380,6 +427,11 @@ extern int set_irq_msi(unsigned int irq, struct msi_desc *entry);
#define get_irq_data(irq) (irq_to_desc(irq)->handler_data)
#define get_irq_msi(irq) (irq_to_desc(irq)->msi_desc)
#define get_irq_desc_chip(desc) ((desc)->chip)
#define get_irq_desc_chip_data(desc) ((desc)->chip_data)
#define get_irq_desc_data(desc) ((desc)->handler_data)
#define get_irq_desc_msi(desc) ((desc)->msi_desc)
#endif /* CONFIG_GENERIC_HARDIRQS */
#endif /* !CONFIG_S390 */