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| author | David Rientjes <rientjes@google.com> | 2016-12-12 16:42:20 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 18:55:07 -0800 |
| commit | fd60775aea802beef444881ddfa111a4b73b1bbc (patch) | |
| tree | db96e02edd1a97205c8b420d7309d2956e6f0e3a /mm/mprotect.c | |
| parent | 3f5000693f80e014fa577b67b93a0de945a4338d (diff) | |
| download | lwn-fd60775aea802beef444881ddfa111a4b73b1bbc.tar.gz lwn-fd60775aea802beef444881ddfa111a4b73b1bbc.zip | |
mm, thp: avoid unlikely branches for split_huge_pmd
While doing MADV_DONTNEED on a large area of thp memory, I noticed we
encountered many unlikely() branches in profiles for each backing
hugepage. This is because zap_pmd_range() would call split_huge_pmd(),
which rechecked the conditions that were already validated, but as part
of an unlikely() branch.
Avoid the unlikely() branch when in a context where pmd is known to be
good for __split_huge_pmd() directly.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1610181600300.84525@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c index 05a02b72c98d..c5ba2aae0f54 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -176,7 +176,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { if (next - addr != HPAGE_PMD_SIZE) { - split_huge_pmd(vma, pmd, addr); + __split_huge_pmd(vma, pmd, addr, false, NULL); if (pmd_trans_unstable(pmd)) continue; } else { |