[PATCH v5 24/25] arm64/mm: __always_inline to improve fork() perf

Ryan Roberts
2024-02-02T08:09:48Z

As set_ptes() and wrprotect_ptes() become a bit more complex, the
compiler may choose not to inline them. But this is critical for fork()
performance. So mark the functions, along with contpte_try_unfold()
which is called by them, as __always_inline. This is worth ~1% on the
fork() microbenchmark with order-0 folios (the common case).

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
arch/arm64/include/asm/pgtable.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 353ea67b5d75..cdc310880a3b 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1213,8 +1213,8 @@ extern int contpte_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t entry, int dirty);

-static inline void contpte_try_unfold(struct mm_struct *mm, unsigned long addr,
- pte_t *ptep, pte_t pte)
+static __always_inline void contpte_try_unfold(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep, pte_t pte)
{
if (unlikely(pte_valid_cont(pte)))
__contpte_try_unfold(mm, addr, ptep, pte);
@@ -1279,7 +1279,7 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
}

#define set_ptes set_ptes
-static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+static __always_inline void set_ptes(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte, unsigned int nr)
{
pte = pte_mknoncont(pte);
@@ -1361,8 +1361,8 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
}

#define wrprotect_ptes wrprotect_ptes
-static inline void wrprotect_ptes(struct mm_struct *mm, unsigned long addr,
- pte_t *ptep, unsigned int nr)
+static __always_inline void wrprotect_ptes(struct mm_struct *mm,
+ unsigned long addr, pte_t *ptep, unsigned int nr)
{
if (likely(nr == 1)) {
/*
--
2.25.1