x86: Increase NR_IRQS and nr_irqs

I have a system with lots of igb and ixgbe, when iov/vf are
enabled for them, we hit the limit of 3064.

when system has 20 pcie installed, and one card has 2
functions, and one function needs 64 msi-x,
 may need 20 * 2 * 64 = 2560 for msi-x

but if iov and vf are enabled
 may need 20 * 2 * 64 * 3 = 7680 for msi-x
assume system with 5 ioapic, nr_irqs_gsi will be 120.

NR_CPUS = 512, and nr_cpu_ids = 128
will have NR_IRQS = 256 + 512 * 64 = 33024
will have nr_irqs = 120 + 8 * 128 + 120 * 64 = 8824

When SPARSE_IRQ is not set, there is no increase with kernel data
size.

when NR_CPUS=128, and SPARSE_IRQ is set:
   text		   data	    bss		   dec		 hex	filename
21837444	4216564	12480736	38534744	24bfe58	vmlinux.before
21837442	4216580	12480736	38534758	24bfe66	vmlinux.after
when NR_CPUS=4096, and SPARSE_IRQ is set
   text		   data	    bss		   dec		 hex	filename
21878619	5610244	13415392	40904255	270263f	vmlinux.before
21878617	5610244	13415392	40904253	270263d	vmlinux.after
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B398ECD.1080506@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/irq_vectors.h

@@ -154,21 +154,21 @@ static inline int invalid_vm86_irq(int irq)
 
 #define NR_IRQS_LEGACY			  16
 
-#define CPU_VECTOR_LIMIT		(  8 * NR_CPUS      )
 #define IO_APIC_VECTOR_LIMIT		( 32 * MAX_IO_APICS )
 
 #ifdef CONFIG_X86_IO_APIC
 # ifdef CONFIG_SPARSE_IRQ
+#  define CPU_VECTOR_LIMIT		(64 * NR_CPUS)
 #  define NR_IRQS					\
 	(CPU_VECTOR_LIMIT > IO_APIC_VECTOR_LIMIT ?	\
 		(NR_VECTORS + CPU_VECTOR_LIMIT)  :	\
 		(NR_VECTORS + IO_APIC_VECTOR_LIMIT))
 # else
-#  if NR_CPUS < MAX_IO_APICS
-#   define NR_IRQS 			(NR_VECTORS + 4*CPU_VECTOR_LIMIT)
-#  else
-#   define NR_IRQS			(NR_VECTORS + IO_APIC_VECTOR_LIMIT)
-#  endif
+#  define CPU_VECTOR_LIMIT		(32 * NR_CPUS)
+#  define NR_IRQS					\
+	(CPU_VECTOR_LIMIT < IO_APIC_VECTOR_LIMIT ?	\
+		(NR_VECTORS + CPU_VECTOR_LIMIT)  :	\
+		(NR_VECTORS + IO_APIC_VECTOR_LIMIT))
 # endif
 #else /* !CONFIG_X86_IO_APIC: */
 # define NR_IRQS			NR_IRQS_LEGACY

arch/x86/kernel/apic/io_apic.c

@@ -3840,7 +3840,7 @@ int __init arch_probe_nr_irqs(void)
 	/*
 	 * for MSI and HT dyn irq
 	 */
-	nr += nr_irqs_gsi * 16;
+	nr += nr_irqs_gsi * 64;
 #endif
 	if (nr < nr_irqs)
 		nr_irqs = nr;