x86: arch_probe_nr_irqs
Impact: save RAM with large NR_CPUS, get smaller nr_irqs
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Mike Travis <travis@sgi.com>
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 602361a..a16a2ab 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -115,14 +115,11 @@
# endif
#else
-/* defined as a macro so nr_irqs = max_nr_irqs(nr_cpu_ids) can be used */
-# define max_nr_irqs(nr_cpus) \
- ((8 * nr_cpus) > (32 * MAX_IO_APICS) ? \
+# define NR_IRQS \
+ ((8 * NR_CPUS) > (32 * MAX_IO_APICS) ? \
(NR_VECTORS + (8 * NR_CPUS)) : \
(NR_VECTORS + (32 * MAX_IO_APICS))) \
-# define NR_IRQS max_nr_irqs(NR_CPUS)
-
#endif
#elif defined(CONFIG_X86_VOYAGER)
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index ae806380..1579869 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3850,6 +3850,22 @@
nr_irqs_gsi = nr;
}
+#ifdef CONFIG_SPARSE_IRQ
+int __init arch_probe_nr_irqs(void)
+{
+ int nr;
+
+ nr = ((8 * nr_cpu_ids) > (32 * nr_ioapics) ?
+ (NR_VECTORS + (8 * nr_cpu_ids)) :
+ (NR_VECTORS + (32 * nr_ioapics)));
+
+ if (nr < nr_irqs && nr > nr_irqs_gsi)
+ nr_irqs = nr;
+
+ return 0;
+}
+#endif
+
/* --------------------------------------------------------------------------
ACPI-based IOAPIC Configuration
-------------------------------------------------------------------------- */
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 9127f6b..472f117 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -467,6 +467,7 @@
struct irq_desc;
extern int early_irq_init(void);
+extern int arch_probe_nr_irqs(void);
extern int arch_early_irq_init(void);
extern int arch_init_chip_data(struct irq_desc *desc, int cpu);
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 04d3e46..375d68c 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -59,10 +59,6 @@
#ifdef CONFIG_SPARSE_IRQ
-#ifndef max_nr_irqs
-#define max_nr_irqs(nr_cpus) NR_IRQS
-#endif
-
static struct irq_desc irq_desc_init = {
.irq = -1,
.status = IRQ_DISABLED,
@@ -137,9 +133,8 @@
int legacy_count;
int i;
- /* initialize nr_irqs based on nr_cpu_ids */
- nr_irqs = max_nr_irqs(nr_cpu_ids);
-
+ /* initialize nr_irqs based on nr_cpu_ids */
+ arch_probe_nr_irqs();
printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d\n", NR_IRQS, nr_irqs);
desc = irq_desc_legacy;
diff --git a/kernel/softirq.c b/kernel/softirq.c
index bdbe9de..0365b48 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -795,6 +795,11 @@
return 0;
}
+int __init __weak arch_probe_nr_irqs(void)
+{
+ return 0;
+}
+
int __init __weak arch_early_irq_init(void)
{
return 0;