Implement the Arm64 architecture-specific test_and_clear_young_ptes() to enable batched checking of young flags, improving performance during large folio reclamation when MGLRU is enabled. While we're at it, simplify ptep_test_and_clear_young() by calling test_and_clear_young_ptes(). Since callers guarantee that PTEs are present before calling these functions, we can use pte_cont() to check the CONT_PTE flag instead of pte_valid_cont(). Performance testing: Enable MGLRU, then 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 60%+ performance improvement on my Arm64 32-core server (and about 15% improvement on my X86 machine). W/o patchset: real 0m0.470s user 0m0.000s sys 0m0.470s W/ patchset: real 0m0.180s user 0m0.001s sys 0m0.179s Signed-off-by: Baolin Wang --- arch/arm64/include/asm/pgtable.h | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index aa4b13da6371..ab451d20e4c5 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -1812,16 +1812,22 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, return __ptep_get_and_clear(mm, addr, ptep); } +#define test_and_clear_young_ptes test_and_clear_young_ptes +static inline int test_and_clear_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)))) + return __ptep_test_and_clear_young(vma, addr, ptep); + + return contpte_test_and_clear_young_ptes(vma, addr, ptep, nr); +} + #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { - pte_t orig_pte = __ptep_get(ptep); - - if (likely(!pte_valid_cont(orig_pte))) - return __ptep_test_and_clear_young(vma, addr, ptep); - - return contpte_test_and_clear_young_ptes(vma, addr, ptep, 1); + return test_and_clear_young_ptes(vma, addr, ptep, 1); } #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH -- 2.47.3