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| author | Abhijit Karmarkar <abhijitk@veritas.com> | 2005-06-21 17:15:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-21 18:46:21 -0700 |
| commit | b4955ce3dd0818b56da532a16c9a4a3804a558ee (patch) | |
| tree | 6e01667181bfc495b56e39748783ad2235a4f56e | |
| parent | c475a8ab625d567eacf5e30ec35d6d8704558062 (diff) | |
| download | lwn-b4955ce3dd0818b56da532a16c9a4a3804a558ee.tar.gz lwn-b4955ce3dd0818b56da532a16c9a4a3804a558ee.zip | |
[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>
| -rw-r--r-- | include/asm-generic/pgtable.h | 3 | ||||
| -rw-r--r-- | mm/msync.c | 2 |
2 files changed, 5 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 1f4ec7b70270..f40593565173 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 090f426bca7d..d0f5a1bce7cb 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; |