From b4955ce3dd0818b56da532a16c9a4a3804a558ee Mon Sep 17 00:00:00 2001 From: Abhijit Karmarkar <abhijitk@veritas.com> Date: Tue, 21 Jun 2005 17:15:13 -0700 Subject: [PATCH] [PATCH] msync: check pte dirty earlier It's common practice to msync a large address range regularly, in which often only a few ptes have actually been dirtied since the previous pass. sync_pte_range then goes much faster if it tests whether pte is dirty before locating and accessing each struct page cacheline; and it is hardly slowed by ptep_clear_flush_dirty repeating that test in the opposite case, when every pte actually is dirty. But beware, s390's pte_dirty always says false, since its dirty bit is kept in the storage key, located via the struct page address. So skip this optimization in its case: use a pte_maybe_dirty macro which just says true if page_test_and_clear_dirty is implemented. Signed-off-by: Abhijit Karmarkar <abhijitk@veritas.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> --- include/asm-generic/pgtable.h | 3 +++ mm/msync.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 1f4ec7b702706..f405935651739 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -125,6 +125,9 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY #define page_test_and_clear_dirty(page) (0) +#define pte_maybe_dirty(pte) pte_dirty(pte) +#else +#define pte_maybe_dirty(pte) (1) #endif #ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG diff --git a/mm/msync.c b/mm/msync.c index 090f426bca7d5..d0f5a1bce7cb1 100644 --- a/mm/msync.c +++ b/mm/msync.c @@ -34,6 +34,8 @@ static void sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd, if (!pte_present(*pte)) continue; + if (!pte_maybe_dirty(*pte)) + continue; pfn = pte_pfn(*pte); if (!pfn_valid(pfn)) continue; -- GitLab