mm: filemap: batch mm counter updating in filemap_map_pages()

Like copy_pte_range()/zap_pte_range(), make mm counter batch updating in
filemap_map_pages(), since folios type are same(MM_SHMEMPAGES or
MM_FILEPAGES) in filemap_map_pages(), only check the first folio type is
enough, the 'lat_pagefault -P 1 file' test from lmbench shows 12%
improvement, and the percpu_counter_add_batch() is gone from perf flame
graph.

Link: https://lkml.kernel.org/r/20240412064751.119015-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index 5a518c5075fb33f3240412e29eeb4392db4dc879..787a2fc6f4aec4c473fbf51a2baf535d85793f52 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3505,7 +3505,7 @@ skip:
 static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
                        struct folio *folio, unsigned long start,
                        unsigned long addr, unsigned int nr_pages,
-                       unsigned int *mmap_miss)
+                       unsigned long *rss, unsigned int *mmap_miss)
 {
        vm_fault_t ret = 0;
        struct page *page = folio_page(folio, start);
@@ -3539,8 +3539,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 skip:
                if (count) {
                        set_pte_range(vmf, folio, page, count, addr);
-                       add_mm_counter(vmf->vma->vm_mm, mm_counter_file(folio),
-                                      count);
+                       *rss += count;
                        folio_ref_add(folio, count);
                        if (in_range(vmf->address, addr, count * PAGE_SIZE))
                                ret = VM_FAULT_NOPAGE;
@@ -3555,7 +3554,7 @@ skip:
 
        if (count) {
                set_pte_range(vmf, folio, page, count, addr);
-               add_mm_counter(vmf->vma->vm_mm, mm_counter_file(folio), count);
+               *rss += count;
                folio_ref_add(folio, count);
                if (in_range(vmf->address, addr, count * PAGE_SIZE))
                        ret = VM_FAULT_NOPAGE;
@@ -3568,7 +3567,7 @@ skip:
 
 static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf,
                struct folio *folio, unsigned long addr,
-               unsigned int *mmap_miss)
+               unsigned long *rss, unsigned int *mmap_miss)
 {
        vm_fault_t ret = 0;
        struct page *page = &folio->page;
@@ -3592,7 +3591,7 @@ static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf,
                ret = VM_FAULT_NOPAGE;
 
        set_pte_range(vmf, folio, page, 1, addr);
-       add_mm_counter(vmf->vma->vm_mm, mm_counter_file(folio), 1);
+       (*rss)++;
        folio_ref_inc(folio);
 
        return ret;
@@ -3609,7 +3608,8 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
        XA_STATE(xas, &mapping->i_pages, start_pgoff);
        struct folio *folio;
        vm_fault_t ret = 0;
-       unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved;
+       unsigned long rss = 0;
+       unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved, folio_type;
 
        rcu_read_lock();
        folio = next_uptodate_folio(&xas, mapping, end_pgoff);
@@ -3628,6 +3628,8 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
                folio_put(folio);
                goto out;
        }
+
+       folio_type = mm_counter_file(folio);
        do {
                unsigned long end;
 
@@ -3639,15 +3641,16 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
 
                if (!folio_test_large(folio))
                        ret |= filemap_map_order0_folio(vmf,
-                                       folio, addr, &mmap_miss);
+                                       folio, addr, &rss, &mmap_miss);
                else
                        ret |= filemap_map_folio_range(vmf, folio,
                                        xas.xa_index - folio->index, addr,
-                                       nr_pages, &mmap_miss);
+                                       nr_pages, &rss, &mmap_miss);
 
                folio_unlock(folio);
                folio_put(folio);
        } while ((folio = next_uptodate_folio(&xas, mapping, end_pgoff)) != NULL);
+       add_mm_counter(vma->vm_mm, folio_type, rss);
        pte_unmap_unlock(vmf->pte, vmf->ptl);
 out:
        rcu_read_unlock();