diff options
author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2006-09-26 02:30:59 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-26 11:48:44 -0400 |
commit | c1e6098b23bb46e2b488fe9a26f831f867157483 (patch) | |
tree | 6bac4d3cfaab3e7153a15d1a24f9211b2de37ba6 /mm/mprotect.c | |
parent | edc79b2a46ed854595e40edcf3f8b37f9f14aa3f (diff) |
[PATCH] mm: optimize the new mprotect() code a bit
mprotect() resets the page protections, which could result in extra write
faults for those pages whose dirty state we track using write faults and are
dirty already.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/mprotect.c')
-rw-r--r-- | mm/mprotect.c | 34 |
1 files changed, 24 insertions, 10 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c index 367b7f6c063..955f9d0e38a 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c | |||
@@ -27,7 +27,8 @@ | |||
27 | #include <asm/tlbflush.h> | 27 | #include <asm/tlbflush.h> |
28 | 28 | ||
29 | static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, | 29 | static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, |
30 | unsigned long addr, unsigned long end, pgprot_t newprot) | 30 | unsigned long addr, unsigned long end, pgprot_t newprot, |
31 | int dirty_accountable) | ||
31 | { | 32 | { |
32 | pte_t *pte, oldpte; | 33 | pte_t *pte, oldpte; |
33 | spinlock_t *ptl; | 34 | spinlock_t *ptl; |
@@ -42,7 +43,14 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, | |||
42 | * bits by wiping the pte and then setting the new pte | 43 | * bits by wiping the pte and then setting the new pte |
43 | * into place. | 44 | * into place. |
44 | */ | 45 | */ |
45 | ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot); | 46 | ptent = ptep_get_and_clear(mm, addr, pte); |
47 | ptent = pte_modify(ptent, newprot); | ||
48 | /* | ||
49 | * Avoid taking write faults for pages we know to be | ||
50 | * dirty. | ||
51 | */ | ||
52 | if (dirty_accountable && pte_dirty(ptent)) | ||
53 | ptent = pte_mkwrite(ptent); | ||
46 | set_pte_at(mm, addr, pte, ptent); | 54 | set_pte_at(mm, addr, pte, ptent); |
47 | lazy_mmu_prot_update(ptent); | 55 | lazy_mmu_prot_update(ptent); |
48 | #ifdef CONFIG_MIGRATION | 56 | #ifdef CONFIG_MIGRATION |
@@ -66,7 +74,8 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd, | |||
66 | } | 74 | } |
67 | 75 | ||
68 | static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, | 76 | static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, |
69 | unsigned long addr, unsigned long end, pgprot_t newprot) | 77 | unsigned long addr, unsigned long end, pgprot_t newprot, |
78 | int dirty_accountable) | ||
70 | { | 79 | { |
71 | pmd_t *pmd; | 80 | pmd_t *pmd; |
72 | unsigned long next; | 81 | unsigned long next; |
@@ -76,12 +85,13 @@ static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud, | |||
76 | next = pmd_addr_end(addr, end); | 85 | next = pmd_addr_end(addr, end); |
77 | if (pmd_none_or_clear_bad(pmd)) | 86 | if (pmd_none_or_clear_bad(pmd)) |
78 | continue; | 87 | continue; |
79 | change_pte_range(mm, pmd, addr, next, newprot); | 88 | change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable); |
80 | } while (pmd++, addr = next, addr != end); | 89 | } while (pmd++, addr = next, addr != end); |
81 | } | 90 | } |
82 | 91 | ||
83 | static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, | 92 | static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, |
84 | unsigned long addr, unsigned long end, pgprot_t newprot) | 93 | unsigned long addr, unsigned long end, pgprot_t newprot, |
94 | int dirty_accountable) | ||
85 | { | 95 | { |
86 | pud_t *pud; | 96 | pud_t *pud; |
87 | unsigned long next; | 97 | unsigned long next; |
@@ -91,12 +101,13 @@ static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd, | |||
91 | next = pud_addr_end(addr, end); | 101 | next = pud_addr_end(addr, end); |
92 | if (pud_none_or_clear_bad(pud)) | 102 | if (pud_none_or_clear_bad(pud)) |
93 | continue; | 103 | continue; |
94 | change_pmd_range(mm, pud, addr, next, newprot); | 104 | change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable); |
95 | } while (pud++, addr = next, addr != end); | 105 | } while (pud++, addr = next, addr != end); |
96 | } | 106 | } |
97 | 107 | ||
98 | static void change_protection(struct vm_area_struct *vma, | 108 | static void change_protection(struct vm_area_struct *vma, |
99 | unsigned long addr, unsigned long end, pgprot_t newprot) | 109 | unsigned long addr, unsigned long end, pgprot_t newprot, |
110 | int dirty_accountable) | ||
100 | { | 111 | { |
101 | struct mm_struct *mm = vma->vm_mm; | 112 | struct mm_struct *mm = vma->vm_mm; |
102 | pgd_t *pgd; | 113 | pgd_t *pgd; |
@@ -110,7 +121,7 @@ static void change_protection(struct vm_area_struct *vma, | |||
110 | next = pgd_addr_end(addr, end); | 121 | next = pgd_addr_end(addr, end); |
111 | if (pgd_none_or_clear_bad(pgd)) | 122 | if (pgd_none_or_clear_bad(pgd)) |
112 | continue; | 123 | continue; |
113 | change_pud_range(mm, pgd, addr, next, newprot); | 124 | change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable); |
114 | } while (pgd++, addr = next, addr != end); | 125 | } while (pgd++, addr = next, addr != end); |
115 | flush_tlb_range(vma, start, end); | 126 | flush_tlb_range(vma, start, end); |
116 | } | 127 | } |
@@ -125,6 +136,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, | |||
125 | unsigned long charged = 0; | 136 | unsigned long charged = 0; |
126 | pgoff_t pgoff; | 137 | pgoff_t pgoff; |
127 | int error; | 138 | int error; |
139 | int dirty_accountable = 0; | ||
128 | 140 | ||
129 | if (newflags == oldflags) { | 141 | if (newflags == oldflags) { |
130 | *pprev = vma; | 142 | *pprev = vma; |
@@ -181,14 +193,16 @@ success: | |||
181 | vma->vm_flags = newflags; | 193 | vma->vm_flags = newflags; |
182 | vma->vm_page_prot = protection_map[newflags & | 194 | vma->vm_page_prot = protection_map[newflags & |
183 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; | 195 | (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; |
184 | if (vma_wants_writenotify(vma)) | 196 | if (vma_wants_writenotify(vma)) { |
185 | vma->vm_page_prot = protection_map[newflags & | 197 | vma->vm_page_prot = protection_map[newflags & |
186 | (VM_READ|VM_WRITE|VM_EXEC)]; | 198 | (VM_READ|VM_WRITE|VM_EXEC)]; |
199 | dirty_accountable = 1; | ||
200 | } | ||
187 | 201 | ||
188 | if (is_vm_hugetlb_page(vma)) | 202 | if (is_vm_hugetlb_page(vma)) |
189 | hugetlb_change_protection(vma, start, end, vma->vm_page_prot); | 203 | hugetlb_change_protection(vma, start, end, vma->vm_page_prot); |
190 | else | 204 | else |
191 | change_protection(vma, start, end, vma->vm_page_prot); | 205 | change_protection(vma, start, end, vma->vm_page_prot, dirty_accountable); |
192 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); | 206 | vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); |
193 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); | 207 | vm_stat_account(mm, newflags, vma->vm_file, nrpages); |
194 | return 0; | 208 | return 0; |