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filemap: batch PTE mappings

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Call set_pte_range() once per contiguous range of the folio instead of
once per page.  This batches the updates to mm counters and the rmap.

With a will-it-scale.page_fault3 like app (change file write fault testing
to read fault testing.  Trying to upstream it to will-it-scale at [1]) got
15% performance gain on a 48C/96T Cascade Lake test box with 96 processes
running against xfs.

Perf data collected before/after the change:
  18.73%--page_add_file_rmap
          |
           --11.60%--__mod_lruvec_page_state
                     |
                     |--7.40%--__mod_memcg_lruvec_state
                     |          |
                     |           --5.58%--cgroup_rstat_updated
                     |
                      --2.53%--__mod_lruvec_state
                                |
                                 --1.48%--__mod_node_page_state

  9.93%--page_add_file_rmap_range
         |
          --2.67%--__mod_lruvec_page_state
                    |
                    |--1.95%--__mod_memcg_lruvec_state
                    |          |
                    |           --1.57%--cgroup_rstat_updated
                    |
                     --0.61%--__mod_lruvec_state
                               |
                                --0.54%--__mod_node_page_state

The running time of __mode_lruvec_page_state() is reduced about 9%.

[1]: https://github.com/antonblanchard/will-it-scale/pull/37

Link: https://lkml.kernel.org/r/20230802151406.3735276-38-willy@infradead.org
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yin Fengwei 2023-08-02 16:14:05 +01:00 committed by Andrew Morton
parent 3bd786f76d
commit 617c28ecab
1 changed files with 29 additions and 14 deletions
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43
mm/filemap.c
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@ -3480,11 +3480,12 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
struct file *file = vma->vm_file;
struct page *page = folio_page(folio, start);
unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
unsigned int ref_count = 0, count = 0;
unsigned int count = 0;
pte_t *old_ptep = vmf->pte;
do {
if (PageHWPoison(page))
continue;
if (PageHWPoison(page + count))
goto skip;
if (mmap_miss > 0)
mmap_miss--;
@ -3494,20 +3495,34 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
* handled in the specific fault path, and it'll prohibit the
* fault-around logic.
*/
if (!pte_none(*vmf->pte))
continue;
if (!pte_none(vmf->pte[count]))
goto skip;
if (vmf->address == addr)
count++;
continue;
skip:
if (count) {
set_pte_range(vmf, folio, page, count, addr);
folio_ref_add(folio, count);
if (in_range(vmf->address, addr, count))
ret = VM_FAULT_NOPAGE;
}
count++;
page += count;
vmf->pte += count;
addr += count * PAGE_SIZE;
count = 0;
} while (--nr_pages > 0);
if (count) {
set_pte_range(vmf, folio, page, count, addr);
folio_ref_add(folio, count);
if (in_range(vmf->address, addr, count))
ret = VM_FAULT_NOPAGE;
}
ref_count++;
set_pte_range(vmf, folio, page, 1, addr);
} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
/* Restore the vmf->pte */
vmf->pte -= nr_pages;
folio_ref_add(folio, ref_count);
vmf->pte = old_ptep;
WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
return ret;