thp: improve order in lru list for split huge page

Put the tail subpages of an isolated hugepage under splitting in the lru reclaim head as they supposedly should be isolated too next. Queues the subpages in physical order in the lru for non isolated hugepages under splitting. That might provide some theoretical cache benefit to the buddy allocator later. Signed-off-by: Shaohua Li <[email protected]> Signed-off-by: Andrea Arcangeli <[email protected]> Cc: David Rientjes <[email protected]> Cc: Johannes Weiner <[email protected]> Cc: Minchan Kim <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
adn770 · Jan 13, 2012 · 4567688 · 4567688
1 parent f21760b
commit 4567688
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Showing 2 changed files with 3 additions and 4 deletions.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
@@ -1228,7 +1228,6 @@ static int __split_huge_page_splitting(struct page *page,
 static void __split_huge_page_refcount(struct page *page)
 {
 	int i;
-	unsigned long head_index = page->index;
 	struct zone *zone = page_zone(page);
 	int zonestat;
 	int tail_count = 0;
@@ -1239,7 +1238,7 @@ static void __split_huge_page_refcount(struct page *page)
 	/* complete memcg works before add pages to LRU */
 	mem_cgroup_split_huge_fixup(page);
 
-	for (i = 1; i < HPAGE_PMD_NR; i++) {
+	for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
 		struct page *page_tail = page + i;
 
 		/* tail_page->_mapcount cannot change */
@@ -1302,7 +1301,7 @@ static void __split_huge_page_refcount(struct page *page)
 		BUG_ON(page_tail->mapping);
 		page_tail->mapping = page->mapping;
 
-		page_tail->index = ++head_index;
+		page_tail->index = page->index + i;
 
 		BUG_ON(!PageAnon(page_tail));
 		BUG_ON(!PageUptodate(page_tail));

diff --git a/mm/swap.c b/mm/swap.c
@@ -681,7 +681,7 @@ void lru_add_page_tail(struct zone* zone,
 		if (likely(PageLRU(page)))
 			list_add(&page_tail->lru, page->lru.prev);
 		else
-			list_add(&page_tail->lru, &lruvec->lists[lru]);
+			list_add(&page_tail->lru, lruvec->lists[lru].prev);
 		__mod_zone_page_state(zone, NR_LRU_BASE + lru,
 				      hpage_nr_pages(page_tail));
 	} else {