powerpc: Disable SPARSE_IRQ by default

The SPARSE_IRQ considerably adds overhead to critical path of IRQ
handling.  However it doesn't benefit much in space for most systems with
limited IRQ_NR.  Should be disabled unless really necessary.

Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 328774bd41ee171706de902d5640721bfc49b0d2..6506bf4fbff13d82d1c66b629638efe435882b3d 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -400,7 +400,7 @@ config IRQ_ALL_CPUS
 
 config SPARSE_IRQ
        bool "Support sparse irq numbering"
-       default y
+       default n
        help
          This enables support for sparse irqs. This is useful for distro
          kernels that want to define a high CONFIG_NR_CPUS value but still
@@ -409,7 +409,7 @@ config SPARSE_IRQ
          ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
            out the irq_desc[] array in a more NUMA-friendly way. )
 
-         If you don't know what to do here, say Y.
+         If you don't know what to do here, say N.
 
 config NUMA
        bool "NUMA support"