Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCH v2 5/6] mm: make clear_huge_page cache clear only around the fault address | Date | Thu, 9 Aug 2012 18:03:02 +0300 |
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From: Andi Kleen <ak@linux.intel.com>
Clearing a 2MB huge page will typically blow away several levels of CPU caches. To avoid this only cache clear the 4K area around the fault address and use a cache avoiding clears for the rest of the 2MB area.
Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- mm/memory.c | 30 +++++++++++++++++++++++++++--- 1 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index b47199a..e9a75c2 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3969,18 +3969,35 @@ EXPORT_SYMBOL(might_fault); #endif #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) + +#ifndef ARCH_HAS_USER_NOCACHE +#define ARCH_HAS_USER_NOCACHE 0 +#endif + +#if ARCH_HAS_USER_NOCACHE == 0 +#define clear_user_highpage_nocache clear_user_highpage +#endif + static void clear_gigantic_page(struct page *page, unsigned long addr, unsigned int pages_per_huge_page) { int i; struct page *p = page; + unsigned long vaddr; + unsigned long haddr = addr & HPAGE_PMD_MASK; + int target = (addr - haddr) >> PAGE_SHIFT; might_sleep(); + vaddr = haddr; for (i = 0; i < pages_per_huge_page; i++, p = mem_map_next(p, page, i)) { cond_resched(); - clear_user_highpage(p, addr + i * PAGE_SIZE); + vaddr = haddr + i*PAGE_SIZE; + if (!ARCH_HAS_USER_NOCACHE || i == target) + clear_user_highpage(p, vaddr); + else + clear_user_highpage_nocache(p, vaddr); } } void clear_huge_page(struct page *page, @@ -3988,16 +4005,23 @@ void clear_huge_page(struct page *page, { int i; unsigned long haddr = addr & HPAGE_PMD_MASK; + unsigned long vaddr; + int target = (addr - haddr) >> PAGE_SHIFT; if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { - clear_gigantic_page(page, haddr, pages_per_huge_page); + clear_gigantic_page(page, addr, pages_per_huge_page); return; } might_sleep(); + vaddr = haddr; for (i = 0; i < pages_per_huge_page; i++) { cond_resched(); - clear_user_highpage(page + i, haddr + i * PAGE_SIZE); + vaddr = haddr + i*PAGE_SIZE; + if (!ARCH_HAS_USER_NOCACHE || i == target) + clear_user_highpage(page + i, vaddr); + else + clear_user_highpage_nocache(page + i, vaddr); } } -- 1.7.7.6
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