On 2/9/26 11:30 PM, David Hildenbrand (Arm) wrote:

On 2/9/26 15:07, Baolin Wang wrote:

quoted

Implement the Arm64 architecture-specific clear_flush_young_ptes() to 
enable
batched checking of young flags and TLB flushing, improving 
performance during
large folio reclamation.

Performance testing:
Allocate 10G clean file-backed folios by mmap() in a memory cgroup, 
and try to
reclaim 8G file-backed folios via the memory.reclaim interface. I can 
observe
33% performance improvement on my Arm64 32-core server (and 10%+ 
improvement
on my X86 machine). Meanwhile, the hotspot folio_check_references() 
dropped
from approximately 35% to around 5%.

W/o patchset:
real    0m1.518s
user    0m0.000s
sys    0m1.518s

W/ patchset:
real    0m1.018s
user    0m0.000s
sys    0m1.018s

Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
  arch/arm64/include/asm/pgtable.h | 11 +++++++++++
  1 file changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/ 

asm/pgtable.h
index 3dabf5ea17fa..a17eb8a76788 100644

--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h

@@ -1838,6 +1838,17 @@ static inline int ptep_clear_flush_young(struct 

vm_area_struct *vma,
      return contpte_clear_flush_young_ptes(vma, addr, ptep, 1);
  }
+#define clear_flush_young_ptes clear_flush_young_ptes
+static inline int clear_flush_young_ptes(struct vm_area_struct *vma,
+                     unsigned long addr, pte_t *ptep,
+                     unsigned int nr)
+{
+    if (likely(nr == 1 && !pte_cont(__ptep_get(ptep))))

I guess similar cases where we should never end up with non-present ptes 
should be updated accordingly.

ptep_test_and_clear_young(), for example, should never be called on non- 
present ptes.

Yes. I already adrressed this in my follow-up patchset.

Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>

Thanks.