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filemap: add filemap_map_folio_range() 

filemap_map_folio_range() maps partial/full folio.  Comparing to original
filemap_map_pages(), it updates refcount once per folio instead of per
page and gets minor performance improvement for large folio.

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 2% performance gain on a 48C/96T Cascade Lake test box with 96
processes running against xfs.

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

Link: https://lkml.kernel.org/r/20230802151406.3735276-35-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 16:14:02 +01:00 committed by Andrew Morton
parent 9f1f5b60e7
commit de74976eb6
1 changed files with 55 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
mm/filemap.c
View File

@ -2168,16 +2168,6 @@ out:
}
EXPORT_SYMBOL(filemap_get_folios);
static inline
bool folio_more_pages(struct folio *folio, pgoff_t index, pgoff_t max)
{
if (!folio_test_large(folio) || folio_test_hugetlb(folio))
return false;
if (index >= max)
return false;
return index < folio_next_index(folio) - 1;
}
/**
* filemap_get_folios_contig - Get a batch of contiguous folios
* @mapping: The address_space to search
@ -3436,10 +3426,10 @@ static bool filemap_map_pmd(struct vm_fault *vmf, struct folio *folio,
return false;
}
static struct folio *next_uptodate_page(struct folio *folio,
struct address_space *mapping,
struct xa_state *xas, pgoff_t end_pgoff)
static struct folio *next_uptodate_folio(struct xa_state *xas,
struct address_space *mapping, pgoff_t end_pgoff)
{
struct folio *folio = xas_next_entry(xas, end_pgoff);
unsigned long max_idx;
do {
@ -3477,20 +3467,51 @@ skip:
return NULL;
}
static inline struct folio *first_map_page(struct address_space *mapping,
struct xa_state *xas,
pgoff_t end_pgoff)
/*
* Map page range [start_page, start_page + nr_pages) of folio.
* start_page is gotten from start by folio_page(folio, start)
*/
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)
{
return next_uptodate_page(xas_find(xas, end_pgoff),
mapping, xas, end_pgoff);
}
vm_fault_t ret = 0;
struct vm_area_struct *vma = vmf->vma;
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;
static inline struct folio *next_map_page(struct address_space *mapping,
struct xa_state *xas,
pgoff_t end_pgoff)
{
return next_uptodate_page(xas_next_entry(xas, end_pgoff),
mapping, xas, end_pgoff);
do {
if (PageHWPoison(page))
continue;
if (mmap_miss > 0)
mmap_miss--;
/*
* NOTE: If there're PTE markers, we'll leave them to be
* handled in the specific fault path, and it'll prohibit the
* fault-around logic.
*/
if (!pte_none(*vmf->pte))
continue;
if (vmf->address == addr)
ret = VM_FAULT_NOPAGE;
ref_count++;
do_set_pte(vmf, page, addr);
update_mmu_cache(vma, addr, vmf->pte);
} while (vmf->pte++, page++, addr += PAGE_SIZE, ++count < nr_pages);
/* Restore the vmf->pte */
vmf->pte -= nr_pages;
folio_ref_add(folio, ref_count);
WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
return ret;
}
vm_fault_t filemap_map_pages(struct vm_fault *vmf,
@ -3503,12 +3524,11 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
unsigned long addr;
XA_STATE(xas, &mapping->i_pages, start_pgoff);
struct folio *folio;
struct page *page;
unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
vm_fault_t ret = 0;
int nr_pages = 0;
rcu_read_lock();
folio = first_map_page(mapping, &xas, end_pgoff);
folio = next_uptodate_folio(&xas, mapping, end_pgoff);
if (!folio)
goto out;
@ -3525,17 +3545,13 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf,
goto out;
}
do {
again:
page = folio_file_page(folio, xas.xa_index);
if (PageHWPoison(page))
goto unlock;
if (mmap_miss > 0)
mmap_miss--;
unsigned long end;
addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
vmf->pte += xas.xa_index - last_pgoff;
last_pgoff = xas.xa_index;
end = folio->index + folio_nr_pages(folio) - 1;
nr_pages = min(end, end_pgoff) - xas.xa_index + 1;
/*
* NOTE: If there're PTE markers, we'll leave them to be
@ -3545,32 +3561,17 @@ again:
if (!pte_none(ptep_get(vmf->pte)))
goto unlock;
/* We're about to handle the fault */
if (vmf->address == addr)
ret = VM_FAULT_NOPAGE;
ret |= filemap_map_folio_range(vmf, folio,
xas.xa_index - folio->index, addr, nr_pages);
do_set_pte(vmf, page, addr);
/* no need to invalidate: a not-present page won't be cached */
update_mmu_cache(vma, addr, vmf->pte);
if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
xas.xa_index++;
folio_ref_inc(folio);
goto again;
}
folio_unlock(folio);
continue;
unlock:
if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
xas.xa_index++;
goto again;
}
folio_unlock(folio);
folio_put(folio);
} while ((folio = next_map_page(mapping, &xas, end_pgoff)) != NULL);
folio = next_uptodate_folio(&xas, mapping, end_pgoff);
} while (folio);
pte_unmap_unlock(vmf->pte, vmf->ptl);
out:
rcu_read_unlock();
WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
return ret;
}
EXPORT_SYMBOL(filemap_map_pages);