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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/irqnr.h
View file

@ -7,18 +7,10 @@
# define for_each_irq_desc(irq, desc) \
for (irq = 0; irq < nr_irqs; irq++)
#else
extern int nr_irqs;
# 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--)
static inline early_sparse_irq_init(void)
{
}
#endif
#define for_each_irq_nr(irq) \
for (irq = 0; irq < nr_irqs; irq++)
#endif