Hi,
>During boot, we populate the page lists by using the page freeing
>mechanism on every individual page. Unfortunately, this is very
>inefficient because the memory manager spends a lot of time coalescing
>pairs of adjacent free pages into bigger blocks.
>
>Rather than adding a single order 0 page at a time, we can take
>advantage of the fact that we know that all the pages are available and
>free up big blocks of pages at a time instead.
>
>Signed-off-by: Chirantan Ekbote <chirantan at chromium.org>
>---
> arch/arm/mm/init.c | 19 +++++++++++++++++-- include/linux/gfp.h | 1
>+
> mm/internal.h | 1 -
> 3 files changed, 18 insertions(+), 3 deletions(-)
>
>diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index
>97c293e..c7fc2d8 100644
>--- a/arch/arm/mm/init.c
>+++ b/arch/arm/mm/init.c
>@@ -22,6 +22,7 @@
> #include <linux/memblock.h>
> #include <linux/dma-contiguous.h>
> #include <linux/sizes.h>
>+#include <linux/bitops.h>
>
> #include <asm/mach-types.h>
> #include <asm/memblock.h>
>@@ -469,8 +470,22 @@ static void __init free_unused_memmap(struct
>meminfo
*mi)
> #ifdef CONFIG_HIGHMEM
> static inline void free_area_high(unsigned long pfn, unsigned long
>end) {
>- for (; pfn < end; pfn++)
>- free_highmem_page(pfn_to_page(pfn));
>+ while (pfn < end) {
>+ struct page *page = pfn_to_page(pfn);
>+ unsigned long order = min(__ffs(pfn), MAX_ORDER - 1);
>+ unsigned long nr_pages = 1 << order;
>+ unsigned long rem = end - pfn;
>+
>+ if (nr_pages > rem) {
>+ order = __fls(rem);
>+ nr_pages = 1 << order;
>+ }
>+
>+ __free_pages_bootmem(page, order);
>+ totalram_pages += nr_pages;
>+ totalhigh_pages += nr_pages;
>+ pfn += nr_pages;
>+ }
> }
> #endif
>
>diff --git a/include/linux/gfp.h b/include/linux/gfp.h index
>39b81dc..a63d666 100644
>--- a/include/linux/gfp.h
>+++ b/include/linux/gfp.h
>@@ -367,6 +367,7 @@ void *alloc_pages_exact_nid(int nid, size_t size,
>gfp_t
gfp_mask);
> #define __get_dma_pages(gfp_mask, order) \
> __get_free_pages((gfp_mask) | GFP_DMA, (order))
>
>+extern void __free_pages_bootmem(struct page *page, unsigned int
>+order);
> extern void __free_pages(struct page *page, unsigned int order);
>extern void free_pages(unsigned long addr, unsigned int order); extern
>void free_hot_cold_page(struct page *page, int cold); diff --git
>a/mm/internal.h b/mm/internal.h index 29e1e76..d2b8738 100644
>--- a/mm/internal.h
>+++ b/mm/internal.h
>@@ -93,7 +93,6 @@ extern pmd_t *mm_find_pmd(struct mm_struct *mm,
>unsigned
long address);
> /*
> * in mm/page_alloc.c
> */
>-extern void __free_pages_bootmem(struct page *page, unsigned int
>order); extern void prep_compound_page(struct page *page, unsigned
>long order); #ifdef CONFIG_MEMORY_FAILURE extern bool
>is_free_buddy_page(struct page *page);
>--
>1.9.1.423.g4596e3a
This patch really could save boot time.
Is there any reason this patch is not merged to mainline kernel?
Best Regards,
Jungseung Lee
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