x86: modify Kconfig to allow up to 4096 cpus
* Increase the limit of NR_CPUS to 4096 and introduce a boolean
called "MAXSMP" which when set (e.g. "allyesconfig"), will set
NR_CPUS = 4096 and NODES_SHIFT = 9 (512).
* Changed max setting for NODES_SHIFT from 15 to 9 to accurately
reflect the real limit.
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bf07b6f..2e32552 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -561,20 +561,35 @@
config IOMMU_HELPER
def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB)
+config MAXSMP
+ bool "Configure Maximum number of SMP Processors and NUMA Nodes"
+ depends on X86_64 && SMP
+ default n
+ help
+ Configure maximum number of CPUS and NUMA Nodes for this architecture.
+ If unsure, say N.
+if MAXSMP
config NR_CPUS
- int "Maximum number of CPUs (2-255)"
- range 2 255
+ int
+ default "4096"
+endif
+
+if !MAXSMP
+config NR_CPUS
+ int "Maximum number of CPUs (2-4096)"
+ range 2 4096
depends on SMP
default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
default "8"
help
This allows you to specify the maximum number of CPUs which this
- kernel will support. The maximum supported value is 255 and the
+ kernel will support. The maximum supported value is 4096 and the
minimum value which makes sense is 2.
This is purely to save memory - each supported CPU adds
approximately eight kilobytes to the kernel image.
+endif
config SCHED_SMT
bool "SMT (Hyperthreading) scheduler support"
@@ -965,13 +980,25 @@
into virtual nodes when booted with "numa=fake=N", where N is the
number of nodes. This is only useful for debugging.
+if MAXSMP
+
config NODES_SHIFT
- int "Max num nodes shift(1-9)"
- range 1 9 if X86_64
+ int
+ default "9"
+endif
+
+if !MAXSMP
+config NODES_SHIFT
+ int "Maximum NUMA Nodes (as a power of 2)"
+ range 1 9 if X86_64
default "6" if X86_64
default "4" if X86_NUMAQ
default "3"
depends on NEED_MULTIPLE_NODES
+ help
+ Specify the maximum number of NUMA Nodes available on the target
+ system. Increases memory reserved to accomodate various tables.
+endif
config HAVE_ARCH_BOOTMEM_NODE
def_bool y