On one of my platforms, linux is given 1152MB memory. With current SECTION_SIZE_BITS 30, the reserved memmap is larger, it's a waste for us. Inspired by disscusion[1], reducing the SECTION_SIZE_BITS to 27 which means 128M section size saves us about 14MB, a huge gain for embeded memory constrained system.
[1]http://lkml.iu.edu/hypermail/linux/kernel/1604.1/03036.html Signed-off-by: Jisheng Zhang <[email protected]> --- arch/arm64/include/asm/sparsemem.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/include/asm/sparsemem.h b/arch/arm64/include/asm/sparsemem.h index 74a9d30..41c10f7 100644 --- a/arch/arm64/include/asm/sparsemem.h +++ b/arch/arm64/include/asm/sparsemem.h @@ -18,7 +18,11 @@ #ifdef CONFIG_SPARSEMEM #define MAX_PHYSMEM_BITS 48 +#ifdef CONFIG_ARM64_64K_PAGES #define SECTION_SIZE_BITS 30 +#else +#define SECTION_SIZE_BITS 27 +#endif #endif #endif -- 2.8.1
