sparse irq_desc[] array: core kernel and x86 changes
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>
diff --git a/include/linux/irqnr.h b/include/linux/irqnr.h
index 452c280..7a299e9 100644
--- a/include/linux/irqnr.h
+++ b/include/linux/irqnr.h
@@ -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