Re: [PATCH 3/3] mm: Introduce HAVE_ARCH_TRANSPARENT_HUGEPAGE

From: Michal Hocko
Date: Wed Sep 12 2012 - 11:32:01 EST


On Tue 11-09-12 17:47:16, Will Deacon wrote:
> From: Steve Capper <steve.capper@xxxxxxx>
>
> Different architectures have slightly different pre-requisites for supporting
> Transparent Huge Pages. To simplify the layout of mm/Kconfig, a new option
> HAVE_ARCH_TRANSPARENT_HUGEPAGE is introduced and set in each architecture's
> Kconfig file (at the moment x86, with ARM being set in a future patch).
>
> Signed-off-by: Steve Capper <steve.capper@xxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>

Makes sense if there are going to be more archs to support THP.
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>

> ---
> arch/x86/Kconfig | 4 ++++
> mm/Kconfig | 2 +-
> 2 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 8ec3a1a..7decdcf 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1297,6 +1297,10 @@ config ILLEGAL_POINTER_VALUE
> default 0 if X86_32
> default 0xdead000000000000 if X86_64
>
> +config HAVE_ARCH_TRANSPARENT_HUGEPAGE
> + def_bool y
> + depends on MMU
> +
> source "mm/Kconfig"
>
> config HIGHPTE
> diff --git a/mm/Kconfig b/mm/Kconfig
> index d5c8019..3322342 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -318,7 +318,7 @@ config NOMMU_INITIAL_TRIM_EXCESS
>
> config TRANSPARENT_HUGEPAGE
> bool "Transparent Hugepage Support"
> - depends on X86 && MMU
> + depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
> select COMPACTION
> help
> Transparent Hugepages allows the kernel to use huge pages and
> --
> 1.7.4.1
>

--
Michal Hocko
SUSE Labs
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