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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>