linux-kernel - [PATCH v6 17/18] arm64/mm: __always

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Message-Id: <20240215103205.2607016-18-ryan.roberts@arm.com>
Date: Thu, 15 Feb 2024 10:32:04 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Ard Biesheuvel <ardb@...nel.org>,
	Marc Zyngier <maz@...nel.org>,
	James Morse <james.morse@....com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Wilcox <willy@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	David Hildenbrand <david@...hat.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	John Hubbard <jhubbard@...dia.com>,
	Zi Yan <ziy@...dia.com>,
	Barry Song <21cnbao@...il.com>,
	Alistair Popple <apopple@...dia.com>,
	Yang Shi <shy828301@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v6 17/18] arm64/mm: __always_inline to improve fork() perf

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).

Acked-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Ryan Roberts <ryan.roberts@....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 d759a20d2929..8310875133ff 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1206,8 +1206,8 @@ 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);
@@ -1278,7 +1278,7 @@ 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);
@@ -1360,8 +1360,8 @@ 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