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arm: mm: enable RCU fast_gup 

Activate the RCU fast_gup for ARM.  We also need to force THP splits to
broadcast an IPI s.t.  we block in the fast_gup page walker.  As THP
splits are comparatively rare, this should not lead to a noticeable
performance degradation.

Some pre-requisite functions pud_write and pud_page are also added.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Steve Capper 2014-10-09 15:29:20 -07:00 committed by Linus Torvalds
parent a0ad5496b2
commit b8cd51afe0
3 changed files with 27 additions and 0 deletions
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4
arch/arm/Kconfig
View File

@ -1661,6 +1661,10 @@ config ARCH_SELECT_MEMORY_MODEL
config HAVE_ARCH_PFN_VALID
def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM
config HAVE_GENERIC_RCU_GUP
def_bool y
depends on ARM_LPAE
config HIGHMEM
bool "High Memory Support"
depends on MMU

8
arch/arm/include/asm/pgtable-3level.h
View File

@ -224,6 +224,8 @@ static inline pte_t pte_mkspecial(pte_t pte)
#define __HAVE_ARCH_PMD_WRITE
#define pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY))
#define pmd_dirty(pmd) (pmd_isset((pmd), L_PMD_SECT_DIRTY))
#define pud_page(pud) pmd_page(__pmd(pud_val(pud)))
#define pud_write(pud) pmd_write(__pmd(pud_val(pud)))
#define pmd_hugewillfault(pmd) (!pmd_young(pmd) || !pmd_write(pmd))
#define pmd_thp_or_huge(pmd) (pmd_huge(pmd) || pmd_trans_huge(pmd))
@ -231,6 +233,12 @@ static inline pte_t pte_mkspecial(pte_t pte)
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#define pmd_trans_huge(pmd) (pmd_val(pmd) && !pmd_table(pmd))
#define pmd_trans_splitting(pmd) (pmd_isset((pmd), L_PMD_SECT_SPLITTING))
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp);
#endif
#endif
#define PMD_BIT_FUNC(fn,op) \

15
arch/arm/mm/flush.c
View File

@ -400,3 +400,18 @@ void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned l
*/
__cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
pmd_t pmd = pmd_mksplitting(*pmdp);
VM_BUG_ON(address & ~PMD_MASK);
set_pmd_at(vma->vm_mm, address, pmdp, pmd);
/* dummy IPI to serialise against fast_gup */
kick_all_cpus_sync();
}
#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */