diff mbox series

[v2,06/14] arm64/mm: Hoist barriers out of set_ptes_anysz() loop

Message ID 20250217140809.1702789-7-ryan.roberts@arm.com (mailing list archive)
State New
Headers show
Series Perf improvements for hugetlb and vmalloc on arm64 | expand

Commit Message

Ryan Roberts Feb. 17, 2025, 2:07 p.m. UTC
set_ptes_anysz() previously called __set_pte() for each PTE in the
range, which would conditionally issue a DSB and ISB to make the new PTE
value immediately visible to the table walker if the new PTE was valid
and for kernel space.

We can do better than this; let's hoist those barriers out of the loop
so that they are only issued once at the end of the loop. We then reduce
the cost by the number of PTEs in the range.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 arch/arm64/include/asm/pgtable.h | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e255a36380dc..e4b1946b261f 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -317,10 +317,8 @@  static inline void __set_pte_nosync(pte_t *ptep, pte_t pte)
 	WRITE_ONCE(*ptep, pte);
 }
 
-static inline void __set_pte(pte_t *ptep, pte_t pte)
+static inline void __set_pte_complete(pte_t pte)
 {
-	__set_pte_nosync(ptep, pte);
-
 	/*
 	 * Only if the new pte is valid and kernel, otherwise TLB maintenance
 	 * or update_mmu_cache() have the necessary barriers.
@@ -331,6 +329,12 @@  static inline void __set_pte(pte_t *ptep, pte_t pte)
 	}
 }
 
+static inline void __set_pte(pte_t *ptep, pte_t pte)
+{
+	__set_pte_nosync(ptep, pte);
+	__set_pte_complete(pte);
+}
+
 static inline pte_t __ptep_get(pte_t *ptep)
 {
 	return READ_ONCE(*ptep);
@@ -647,12 +651,14 @@  static inline void set_ptes_anysz(struct mm_struct *mm, pte_t *ptep, pte_t pte,
 
 	for (;;) {
 		__check_safe_pte_update(mm, ptep, pte);
-		__set_pte(ptep, pte);
+		__set_pte_nosync(ptep, pte);
 		if (--nr == 0)
 			break;
 		ptep++;
 		pte = pte_advance_pfn(pte, stride);
 	}
+
+	__set_pte_complete(pte);
 }
 
 static inline void __set_ptes(struct mm_struct *mm,