Commit 3a12146d authored by Kefeng Wang's avatar Kefeng Wang Committed by Peng Zhang
Browse files

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

maillist inclusion
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/I9GBVL
CVE: NA

Reference: https://lore.kernel.org/all/20240412064751.119015-3-wangkefeng.wang@huawei.com/



--------------------------------

Like copy_pte_range()/zap_pte_range(), make mm counter batch updating
in filemap_map_pages(), the 'lat_pagefault -P 1 file' test from lmbench
shows 12% improvement, and the percpu_counter_add_batch() is gone from
perf flame graph.

Signed-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
parent 7b9b3094

mm/filemap.c

+12 −9
Original line number Diff line number Diff line
@@ -3474,7 +3474,7 @@ static struct folio *next_uptodate_folio(struct xa_state *xas, 
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);
@@ -3500,8 +3500,7 @@ 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;
@@ -3516,7 +3515,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, 


	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;
@@ -3529,7 +3528,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, 


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;
@@ -3551,7 +3550,7 @@ 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;
@@ -3568,7 +3567,8 @@ 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);
@@ -3587,6 +3587,8 @@ 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;
@@ -3598,15 +3600,16 @@ 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();