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| author | Dave Hansen <dave@linux.vnet.ibm.com> | 2011-03-22 16:32:56 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-03-22 17:44:04 -0700 |
| commit | 033193275b3ffcfe7f3fde7b569f3d207f6cd6a0 (patch) | |
| tree | fc65fa02248f855f0f63e087f35a507b6abb5617 /fs/proc/task_mmu.c | |
| parent | 278df9f451dc71dcd002246be48358a473504ad0 (diff) | |
| download | linux-033193275b3ffcfe7f3fde7b569f3d207f6cd6a0.tar.gz linux-033193275b3ffcfe7f3fde7b569f3d207f6cd6a0.tar.bz2 linux-033193275b3ffcfe7f3fde7b569f3d207f6cd6a0.zip | |
pagewalk: only split huge pages when necessary
Right now, if a mm_walk has either ->pte_entry or ->pmd_entry set, it will
unconditionally split any transparent huge pages it runs in to. In
practice, that means that anyone doing a
cat /proc/$pid/smaps
will unconditionally break down every huge page in the process and depend
on khugepaged to re-collapse it later. This is fairly suboptimal.
This patch changes that behavior. It teaches each ->pmd_entry handler
(there are five) that they must break down the THPs themselves. Also, the
_generic_ code will never break down a THP unless a ->pte_entry handler is
actually set.
This means that the ->pmd_entry handlers can now choose to deal with THPs
without breaking them down.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Eric B Munson <emunson@mgebm.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Cc: Michael J Wolf <mjwolf@us.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/task_mmu.c')
| -rw-r--r-- | fs/proc/task_mmu.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 60b914860f81..78fd3621f565 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -343,6 +343,8 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct page *page; int mapcount; + split_huge_page_pmd(walk->mm, pmd); + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) { ptent = *pte; @@ -467,6 +469,8 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr, spinlock_t *ptl; struct page *page; + split_huge_page_pmd(walk->mm, pmd); + pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); for (; addr != end; pte++, addr += PAGE_SIZE) { ptent = *pte; @@ -623,6 +627,8 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, pte_t *pte; int err = 0; + split_huge_page_pmd(walk->mm, pmd); + /* find the first VMA at or above 'addr' */ vma = find_vma(walk->mm, addr); for (; addr != end; addr += PAGE_SIZE) { |