Messages in this thread Patch in this message | | | From | Jiang Liu <> | Subject | [PATCH] mm: setup pageblock_order before it's used by sparse | Date | Sat, 30 Jun 2012 17:07:54 +0800 |
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From: Xishi Qiu <qiuxishi@huawei.com>
On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, pageblock_order is a variable with default value of 0. It's set to the right value by set_pageblock_order() in function free_area_init_core().
But pageblock_order may be used by sparse_init() before free_area_init_core() is called along path: sparse_init() ->sparse_early_usemaps_alloc_node() ->usemap_size() ->SECTION_BLOCKFLAGS_BITS ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
The uninitialized pageblock_size will cause memory wasting because usemap_size() returns a much bigger value then it's really needed.
For example, on an Itanium platform, sparse_init() pageblock_order=0 usemap_size=24576 free_area_init_core() before pageblock_order=0, usemap_size=24576 free_area_init_core() after pageblock_order=12, usemap_size=8
That means 24K memory has been wasted for each section, so fix it by calling set_pageblock_order() from sparse_init().
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Jiang Liu <liuj97@gmail.com> --- mm/internal.h | 2 ++ mm/page_alloc.c | 4 ++-- mm/sparse.c | 3 +++ 3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/internal.h b/mm/internal.h index 2ba87fb..8052379 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -347,3 +347,5 @@ extern u32 hwpoison_filter_enable; extern unsigned long vm_mmap_pgoff(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); + +extern void set_pageblock_order(void); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4403009..f38509b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4301,7 +4301,7 @@ static inline void setup_usemap(struct pglist_data *pgdat, #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */ -static inline void __init set_pageblock_order(void) +void __init set_pageblock_order(void) { unsigned int order; @@ -4329,7 +4329,7 @@ static inline void __init set_pageblock_order(void) * include/linux/pageblock-flags.h for the values of pageblock_order based on * the kernel config */ -static inline void set_pageblock_order(void) +void __init set_pageblock_order(void) { } diff --git a/mm/sparse.c b/mm/sparse.c index fca2ab5..3a3af73 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -485,6 +485,9 @@ void __init sparse_init(void) struct page **map_map; #endif + /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ + set_pageblock_order(); + /* * map is using big page (aka 2M in x86 64 bit) * usemap is less one page (aka 24 bytes) -- 1.7.1
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