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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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14
include/linux/kernel_stat.h
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@ -28,7 +28,9 @@ struct cpu_usage_stat {
struct kernel_stat {
struct cpu_usage_stat cpustat;
unsigned int irqs[NR_IRQS];
#ifndef CONFIG_SPARSE_IRQ
unsigned int irqs[NR_IRQS];
#endif
};
DECLARE_PER_CPU(struct kernel_stat, kstat);
@ -39,6 +41,10 @@ DECLARE_PER_CPU(struct kernel_stat, kstat);
extern unsigned long long nr_context_switches(void);
#ifndef CONFIG_SPARSE_IRQ
#define kstat_irqs_this_cpu(irq) \
(kstat_this_cpu.irqs[irq])
struct irq_desc;
static inline void kstat_incr_irqs_this_cpu(unsigned int irq,
@ -46,11 +52,17 @@ static inline void kstat_incr_irqs_this_cpu(unsigned int irq,
{
kstat_this_cpu.irqs[irq]++;
}
#endif
#ifndef CONFIG_SPARSE_IRQ
static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
return kstat_cpu(cpu).irqs[irq];
}
#else
extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
#endif
/*
* Number of interrupts per specific IRQ source, since bootup