shmem_insert_pages() currently loops over the array of pages passed
to it and calls shmem_add_to_page_cache() for each one. Prepare
for adding pages to the pagecache in bulk by adding and using a
shmem_add_pages_to_cache() call. For now it just iterates over
an array and adds pages individually, but improvements in performance
when multiple threads are adding to the same pagecache are achieved
by calling a new shmem_add_to_page_cache_fast() function that does
not check for conflicts and drops the xarray lock before updating stats.
Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
---
mm/shmem.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 84 insertions(+), 11 deletions(-)
diff --git a/mm/shmem.c b/mm/shmem.c
index 678a396ba8d3..f621d863e362 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -660,6 +660,57 @@ static int shmem_add_to_page_cache(struct page *page,
return 0;
}
+static int shmem_add_to_page_cache_fast(struct page *page,
+ struct address_space *mapping,
+ pgoff_t index, gfp_t gfp)
+{
+ XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
+ unsigned long nr = compound_nr(page);
+ unsigned long i = 0;
+
+ VM_BUG_ON_PAGE(PageTail(page), page);
+ VM_BUG_ON_PAGE(index != round_down(index, nr), page);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+ page_ref_add(page, nr);
+ page->mapping = mapping;
+ page->index = index;
+
+ do {
+ xas_lock_irq(&xas);
+ xas_create_range(&xas);
+ if (xas_error(&xas))
+ goto unlock;
+next:
+ xas_store(&xas, page);
+ if (++i < nr) {
+ xas_next(&xas);
+ goto next;
+ }
+ mapping->nrpages += nr;
+ xas_unlock(&xas);
+ if (PageTransHuge(page)) {
+ count_vm_event(THP_FILE_ALLOC);
+ __inc_node_page_state(page, NR_SHMEM_THPS);
+ }
+ __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
+ __mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
+ local_irq_enable();
+ break;
+unlock:
+ xas_unlock_irq(&xas);
+ } while (xas_nomem(&xas, gfp));
+
+ if (xas_error(&xas)) {
+ page->mapping = NULL;
+ page_ref_sub(page, nr);
+ return xas_error(&xas);
+ }
+
+ return 0;
+}
+
/*
* Like delete_from_page_cache, but substitutes swap for page.
*/
@@ -681,6 +732,35 @@ static void shmem_delete_from_page_cache(struct page *page, void *radswap)
BUG_ON(error);
}
+static int shmem_add_pages_to_cache(struct page *pages[], int npages,
+ struct address_space *mapping,
+ pgoff_t start, gfp_t gfp)
+{
+ pgoff_t index = start;
+ int err = 0;
+ int i;
+
+ i = 0;
+ while (i < npages) {
+ if (PageTransHuge(pages[i])) {
+ err = shmem_add_to_page_cache_fast(pages[i], mapping, index, gfp);
+ if (err)
+ break;
+ index += HPAGE_PMD_NR;
+ i++;
+ continue;
+ }
+
+ err = shmem_add_to_page_cache_fast(pages[i], mapping, index, gfp);
+ if (err)
+ break;
+ index++;
+ i++;
+ }
+
+ return err;
+}
+
int shmem_insert_page(struct mm_struct *mm, struct inode *inode, pgoff_t index,
struct page *page)
{
@@ -844,17 +924,10 @@ int shmem_insert_pages(struct mm_struct *mm, struct inode *inode, pgoff_t index,
}
- for (i = 0; i < npages; i++) {
- err = shmem_add_to_page_cache(pages[i], mapping, index,
- NULL, gfp & GFP_RECLAIM_MASK);
- if (err)
- goto out_truncate;
-
- if (PageTransHuge(pages[i]))
- index += HPAGE_PMD_NR;
- else
- index++;
- }
+ err = shmem_add_pages_to_cache(pages, npages, mapping, index,
+ gfp & GFP_RECLAIM_MASK);
+ if (err)
+ goto out_truncate;
spin_lock(&info->lock);
info->alloced += nr;
--
2.13.3
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