GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-20 21:51:05 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

mm, thp: avoid unlikely branches for split_huge_pmd

Browse source 
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>
This commit is contained in:
David Rientjes 2016-12-12 16:42:20 -08:00 • committed by Linus Torvalds
parent 3f5000693f
commit fd60775aea
4 changed files with 6 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

2
include/linux/huge_mm.h
View file

@ -189,6 +189,8 @@ static inline void deferred_split_huge_page(struct page *page) {}
#define split_huge_pmd(__vma, __pmd, __address) \
do { } while (0)
static inline void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long address, bool freeze, struct page *page) {}
static inline void split_huge_pmd_address(struct vm_area_struct *vma,
unsigned long address, bool freeze, struct page *page) {}