[RFC PATCH 2/3] mm/mincore: Use can_pte_batch_count() in mincore_pte_range() for pte batch mincore_pte_range()

[Zhang Qilong <zhangqilong3@huawei.com>]

In current mincore_pte_range(), if pte_batch_hint() return one
pte, it's not efficient, just call new added can_pte_batch_count().

In ARM64 qemu, with 8 CPUs, 32G memory, a simple test demo like:
1. mmap 1G anon memory
2. write 1G data by 4k step
3. mincore the mmaped 1G memory
4. get the time consumed by mincore

Tested the following cases:
 - 4k, disabled all hugepage setting.
 - 64k mTHP, only enable 64k hugepage setting.

Before

Case status | Consumed time (us)  |
----------------------------------|
4k          | 7356                |
64k mTHP    | 3670                |

Pathed:

Case status | Consumed time (us)  |
----------------------------------|
4k          | 4419                |
64k mTHP    | 3061                |

The result is evident and demonstrate a significant improvement in
the pte batch. While verification within a single environment may
have inherent randomness. there is a high probability of achieving
positive effects.

Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
---
 mm/mincore.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/mm/mincore.c b/mm/mincore.c
index 8ec4719370e1..2cc5d276d1cd 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -178,18 +178,14 @@ static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		/* We need to do cache lookup too for pte markers */
 		if (pte_none_mostly(pte))
 			__mincore_unmapped_range(addr, addr + PAGE_SIZE,
 						 vma, vec);
 		else if (pte_present(pte)) {
-			unsigned int batch = pte_batch_hint(ptep, pte);
-
-			if (batch > 1) {
-				unsigned int max_nr = (end - addr) >> PAGE_SHIFT;
-
-				step = min_t(unsigned int, batch, max_nr);
-			}
+			unsigned int max_nr = (end - addr) >> PAGE_SHIFT;
 
+			step = can_pte_batch_count(vma, ptep, &pte,
+						   max_nr, 0);
 			for (i = 0; i < step; i++)
 				vec[i] = 1;
 		} else { /* pte is a swap entry */
 			*vec = mincore_swap(pte_to_swp_entry(pte), false);
 		}
-- 
2.43.0