[PATCH 4/9] 00mm5 combine flush accessed dirty.patch
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From: Zachary Amsden <hidden>
Date: 2006-08-11 09:19:00
Also in:
linux-mm, lkml
Remove ptep_test_and_clear_{dirty|young} from i386, and instead use the
dominating functions, ptep_clear_flush_{dirty|young}. This allows the
TLB page flush to be contained in the same macro, and allows for an
eager optimization - if reading the PTE initially returned dirty/accessed,
we can assume the fact that no subsequent update to the PTE which cleared
accessed / dirty has occurred, as the only way A/D bits can change without
holding the page table lock is if a remote processor clears them. This
eliminates an extra branch which came from the generic version of the
code, as we know that no other CPU could have cleared the A/D bit, so the
flush will always be needed.
We still export these two defines, even though we do not actually define
the macros in the i386 code:
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY
The reason for this is that the only use of these functions is within the
generic clear_flush functions, and we want a strong guarantee that there
are no other users of these functions, so we want to prevent the generic
code from defining them for us.
Signed-off-by: Zachary Amsden <redacted>
===================================================================--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h@@ -262,21 +262,36 @@ do { \ } \ } while (0) +/* + * We don't actually have these, but we want to advertise them so that + * we can encompass the flush here. + */ #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY -static inline int ptep_test_and_clear_dirty(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) -{ - if (!pte_dirty(*ptep)) - return 0; - return test_and_clear_bit(_PAGE_BIT_DIRTY, &ptep->pte_low); -} - #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG -static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) -{ - if (!pte_young(*ptep)) - return 0; - return test_and_clear_bit(_PAGE_BIT_ACCESSED, &ptep->pte_low); -} + +#define __HAVE_ARCH_PTEP_CLEAR_DIRTY_FLUSH +#define ptep_clear_flush_dirty(vma, address, ptep) \ +({ \ + int __dirty; \ + __dirty = pte_dirty(*(ptep)); \ + if (__dirty) { \ + clear_bit(_PAGE_BIT_DIRTY, &(ptep)->pte_low); \ + flush_tlb_page(vma, address); \ + } \ + __dirty; \ +}) + +#define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH +#define ptep_clear_flush_young(vma, address, ptep) \ +({ \ + int __young; \ + __young = pte_young(*(ptep)); \ + if (__young) { \ + clear_bit(_PAGE_BIT_ACCESSED, &(ptep)->pte_low); \ + flush_tlb_page(vma, address); \ + } \ + __young; \ +}) #define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long addr, pte_t *ptep, int full)