The patch titled
Subject: arm: mm: enable RCU fast_gup
has been added to the -mm tree. Its filename is
arm-mm-enable-rcu-fast_gup.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/arm-mm-enable-rcu-fast_gup.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/arm-mm-enable-rcu-fast_gup.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Steve Capper <steve.capper@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dann Frazier <dann.frazier@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/Kconfig | 4 ++++
arch/arm/include/asm/pgtable-3level.h | 8 ++++++++
arch/arm/mm/flush.c | 15 +++++++++++++++
3 files changed, 27 insertions(+)
diff -puN arch/arm/Kconfig~arm-mm-enable-rcu-fast_gup arch/arm/Kconfig
--- a/arch/arm/Kconfig~arm-mm-enable-rcu-fast_gup
+++ a/arch/arm/Kconfig
@@ -1646,6 +1646,10 @@ 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
diff -puN arch/arm/include/asm/pgtable-3level.h~arm-mm-enable-rcu-fast_gup arch/arm/include/asm/pgtable-3level.h
--- a/arch/arm/include/asm/pgtable-3level.h~arm-mm-enable-rcu-fast_gup
+++ a/arch/arm/include/asm/pgtable-3level.h
@@ -224,6 +224,8 @@ static inline pte_t pte_mkspecial(pte_t
#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
#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) \
diff -puN arch/arm/mm/flush.c~arm-mm-enable-rcu-fast_gup arch/arm/mm/flush.c
--- a/arch/arm/mm/flush.c~arm-mm-enable-rcu-fast_gup
+++ a/arch/arm/mm/flush.c
@@ -400,3 +400,18 @@ void __flush_anon_page(struct vm_area_st
*/
__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 */
_
Patches currently in -mm which might be from steve.capper@xxxxxxxxxx are
mm-introduce-a-general-rcu-get_user_pages_fast.patch
mm-introduce-a-general-rcu-get_user_pages_fast-fix.patch
arm-mm-introduce-special-ptes-for-lpae.patch
arm-mm-enable-have_rcu_table_free-logic.patch
arm-mm-enable-rcu-fast_gup.patch
arm64-mm-enable-have_rcu_table_free-logic.patch
arm64-mm-enable-rcu-fast_gup.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
