[RFC PATCH 5/5] filemap: batched update mm counter,rmap when map file folio

[Yin Fengwei <fengwei.yin@xxxxxxxxx>]

Instead of update mm counter, rmap one by one, batched update
brings some level performance gain.

Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
---
 mm/filemap.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index fe0c226c8b1e..6d9438490025 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3360,28 +3360,52 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 	struct vm_area_struct *vma = vmf->vma;
 	struct file *file = vma->vm_file;
 	unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
-	int ref_count = 0, count = 0;
+	int ref_count = 0, count = 0, maplen = 0;
+	struct page *pg = page;
 
 	do {
-		if (PageHWPoison(page))
+		if (PageHWPoison(page)) {
+			if (maplen) {
+				page_add_file_rmap_range(folio, pg, maplen,
+					vma, false);
+				add_mm_counter(vma->vm_mm,
+					mm_counter_file(pg), maplen);
+			}
+			pg = page + 1;
+			maplen = 0;
 			continue;
+		}
 
 		if (mmap_miss > 0)
 			mmap_miss--;
 
-		if (!pte_none(*vmf->pte))
+		if (!pte_none(*vmf->pte)) {
+			if (maplen) {
+				page_add_file_rmap_range(folio, pg, maplen,
+					vma, false);
+				add_mm_counter(vma->vm_mm,
+					mm_counter_file(pg), maplen);
+			}
+			pg = page + 1;
+			maplen = 0;
 			continue;
+		}
 
 		if (vmf->address == addr)
 			ret = VM_FAULT_NOPAGE;
 
 		ref_count++;
+		maplen++;
 
-		do_set_pte(vmf, page, addr);
+		do_set_pte_entry(vmf, page, addr);
 		update_mmu_cache(vma, addr, vmf->pte);
 
 	} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < len);
 
+	if (maplen) {
+		page_add_file_rmap_range(folio, pg, maplen, vma, false);
+		add_mm_counter(vma->vm_mm, mm_counter_file(pg), maplen);
+	}
 	folio_ref_add(folio, ref_count);
 	WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
 
-- 
2.30.2