[PATCH v3] arm64: NUMA: Kconfig: Increase NODES_SHIFT to 4

[PATCH v3] arm64: NUMA: Kconfig: Increase NODES_SHIFT to 4

[Vanshidhar Konda]

The current arm64 default config limits max NUMA nodes available on
system to 4 (NODES_SHIFT = 2). Today's arm64 systems can reach or
exceed 16 NUMA nodes. To accomodate current hardware and to fit
NODES_SHIFT within page flags on arm64, increase NODES_SHIFT to 4.

Discussion on v1 of the patch:
https://lore.kernel.org/linux-arm-kernel/20201020173409.1266576-1-vanshikonda@os.amperecomputing.com/

-v2: Updated commit message based on discussion
-v3: Updated link to v1 discussion

Signed-off-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f858c352f72a..cffcc677011f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -982,7 +982,7 @@ config NUMA
 config NODES_SHIFT
 	int "Maximum NUMA Nodes (as a power of 2)"
 	range 1 10
-	default "2"
+	default "4"
 	depends on NEED_MULTIPLE_NODES
 	help
 	  Specify the maximum number of NUMA Nodes available on the target
-- 
2.28.0

Re: [PATCH v3] arm64: NUMA: Kconfig: Increase NODES_SHIFT to 4

[Will Deacon]

On Fri, 30 Oct 2020 10:30:50 -0700, Vanshidhar Konda wrote:
> The current arm64 default config limits max NUMA nodes available on
> system to 4 (NODES_SHIFT = 2). Today's arm64 systems can reach or
> exceed 16 NUMA nodes. To accomodate current hardware and to fit
> NODES_SHIFT within page flags on arm64, increase NODES_SHIFT to 4.
> 
> Discussion on v1 of the patch:
> https://lore.kernel.org/linux-arm-kernel/20201020173409.1266576-1-vanshikonda@os.amperecomputing.com/
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64: NUMA: Kconfig: Increase NODES_SHIFT to 4
      https://git.kernel.org/arm64/c/2a13c13b39a8

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev