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| author | Prasanna Meda <pmeda@akamai.com> | 2005-06-21 17:14:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-06-21 18:46:13 -0700 |
| commit | e798c6e87b64d9fdbd5e9f757b1c033223763d9f (patch) | |
| tree | da4cdd7c60acff82d2fcc826cdbae43440a6df44 /mm/madvise.c | |
| parent | b15e0905f2b9964fc7426fecab57445e96021b61 (diff) | |
| download | lwn-e798c6e87b64d9fdbd5e9f757b1c033223763d9f.tar.gz lwn-e798c6e87b64d9fdbd5e9f757b1c033223763d9f.zip | |
[PATCH] madvise: do not split the maps
This attempts to avoid splittings when it is not needed, that is when
vm_flags are same as new flags. The idea is from the <2.6.11 mlock_fixup
and others. This will provide base for the next madvise merging patch.
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/madvise.c')
| -rw-r--r-- | mm/madvise.c | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/mm/madvise.c b/mm/madvise.c index 944b5e52d812..75b81ad1f98c 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -19,6 +19,21 @@ static long madvise_behavior(struct vm_area_struct * vma, unsigned long start, { struct mm_struct * mm = vma->vm_mm; int error = 0; + int new_flags = vma->vm_flags & ~VM_READHINTMASK; + + switch (behavior) { + case MADV_SEQUENTIAL: + new_flags |= VM_SEQ_READ; + break; + case MADV_RANDOM: + new_flags |= VM_RAND_READ; + break; + default: + break; + } + + if (new_flags == vma->vm_flags) + goto out; if (start != vma->vm_start) { error = split_vma(mm, vma, start, 1); @@ -36,17 +51,7 @@ static long madvise_behavior(struct vm_area_struct * vma, unsigned long start, * vm_flags is protected by the mmap_sem held in write mode. */ VM_ClearReadHint(vma); - - switch (behavior) { - case MADV_SEQUENTIAL: - vma->vm_flags |= VM_SEQ_READ; - break; - case MADV_RANDOM: - vma->vm_flags |= VM_RAND_READ; - break; - default: - break; - } + vma->vm_flags = new_flags; out: if (error == -ENOMEM) |