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authorDavid Rientjes <rientjes@google.com>2016-12-13 01:42:20 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-13 03:55:07 +0100
commitfd60775aea802beef444881ddfa111a4b73b1bbc (patch)
treedb96e02edd1a97205c8b420d7309d2956e6f0e3a /mm/memory.c
parentmm/vmalloc.c: simplify /proc/vmallocinfo implementation (diff)
downloadlinux-fd60775aea802beef444881ddfa111a4b73b1bbc.tar.xz
linux-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/memory.c')
-rw-r--r--mm/memory.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 33f45edf8272..d86b7b4afd7d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1240,7 +1240,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
if (next - addr != HPAGE_PMD_SIZE) {
VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
- split_huge_pmd(vma, pmd, addr);
+ __split_huge_pmd(vma, pmd, addr, false, NULL);
} else if (zap_huge_pmd(tlb, vma, pmd, addr))
goto next;
/* fall through */
@@ -3454,7 +3454,7 @@ static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd)
/* COW handled on pte level: split pmd */
VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma);
- split_huge_pmd(fe->vma, fe->pmd, fe->address);
+ __split_huge_pmd(fe->vma, fe->pmd, fe->address, false, NULL);
return VM_FAULT_FALLBACK;
}