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/irq.h b/include/linux/irq.h
index 3dddfa7..63b0043 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -129,6 +129,8 @@
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_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 @@
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 @@
#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 */