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SubjectRe: [PATCH] mm: memmap_init_zone() performance improvement
On 10/03/2012 10:56 PM, Mike Yoknis wrote:
> memmap_init_zone() loops through every Page Frame Number (pfn),
> including pfn values that are within the gaps between existing
> memory sections. The unneeded looping will become a boot
> performance issue when machines configure larger memory ranges
> that will contain larger and more numerous gaps.
>
> The code will skip across invalid sections to reduce the
> number of loops executed.

looks reasonable to me.

>
> Signed-off-by: Mike Yoknis <mike.yoknis@hp.com>
> ---
> arch/x86/include/asm/mmzone_32.h | 2 ++
> arch/x86/include/asm/page_32.h | 1 +
> arch/x86/include/asm/page_64_types.h | 3 ++-
> include/asm-generic/page.h | 1 +
> include/linux/mmzone.h | 6 ++++++
> mm/page_alloc.c | 5 ++++-
> 6 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/mmzone_32.h b/arch/x86/include/asm/mmzone_32.h
> index eb05fb3..73c5c74 100644
> --- a/arch/x86/include/asm/mmzone_32.h
> +++ b/arch/x86/include/asm/mmzone_32.h
> @@ -48,6 +48,8 @@ static inline int pfn_to_nid(unsigned long pfn)
> #endif
> }
>
> +#define next_pfn_try(pfn) ((pfn)+1)
> +
> static inline int pfn_valid(int pfn)
> {
> int nid = pfn_to_nid(pfn);
> diff --git a/arch/x86/include/asm/page_32.h b/arch/x86/include/asm/page_32.h
> index da4e762..e2c4cfc 100644
> --- a/arch/x86/include/asm/page_32.h
> +++ b/arch/x86/include/asm/page_32.h
> @@ -19,6 +19,7 @@ extern unsigned long __phys_addr(unsigned long);
>
> #ifdef CONFIG_FLATMEM
> #define pfn_valid(pfn) ((pfn) < max_mapnr)
> +#define next_pfn_try(pfn) ((pfn)+1)
> #endif /* CONFIG_FLATMEM */
>
> #ifdef CONFIG_X86_USE_3DNOW
> diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
> index 320f7bb..02d82e5 100644
> --- a/arch/x86/include/asm/page_64_types.h
> +++ b/arch/x86/include/asm/page_64_types.h
> @@ -69,7 +69,8 @@ extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
> #endif /* !__ASSEMBLY__ */
>
> #ifdef CONFIG_FLATMEM
> -#define pfn_valid(pfn) ((pfn) < max_pfn)
> +#define pfn_valid(pfn) ((pfn) < max_pfn)
> +#define next_pfn_try(pfn) ((pfn)+1)
> #endif
>
> #endif /* _ASM_X86_PAGE_64_DEFS_H */
> diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h
> index 37d1fe2..316200d 100644
> --- a/include/asm-generic/page.h
> +++ b/include/asm-generic/page.h
> @@ -91,6 +91,7 @@ extern unsigned long memory_end;
> #endif
>
> #define pfn_valid(pfn) ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
> +#define next_pfn_try(pfn) ((pfn)+1)
>
> #define virt_addr_valid(kaddr) (((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
> ((void *)(kaddr) < (void *)memory_end))
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index f7d88ba..04d3c39 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1166,6 +1166,12 @@ static inline int pfn_valid(unsigned long pfn)
> return 0;
> return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
> }
> +
> +static inline unsigned long next_pfn_try(unsigned long pfn)
> +{
> + /* Skip entire section, because all of it is invalid. */
> + return section_nr_to_pfn(pfn_to_section_nr(pfn) + 1);
> +}
> #endif
>
> static inline int pfn_present(unsigned long pfn)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 5b6b6b1..dd2af8b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3798,8 +3798,11 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
> * exist on hotplugged memory.
> */
> if (context == MEMMAP_EARLY) {
> - if (!early_pfn_valid(pfn))
> + if (!early_pfn_valid(pfn)) {
> + pfn = next_pfn_try(pfn);
> + pfn--;
> continue;
> + }
> if (!early_pfn_in_nid(pfn, nid))
> continue;
> }



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