linux-kernel - [PATCH 7/7] mm: Use free_unref_folios() in put_pages

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Date:   Mon, 21 Aug 2023 21:44:25 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Mateusz Guzik <mjguzik@...il.com>, linux-kernel@...r.kernel.org,
        dennis@...nel.org, tj@...nel.org, cl@...ux.com,
        akpm@...ux-foundation.org, shakeelb@...gle.com, linux-mm@...ck.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Subject: [PATCH 7/7] mm: Use free_unref_folios() in put_pages_list()

Break up the list of folios into batches here so that the
folios are more likely to be cache hot when doing the
rest of the processing.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 mm/swap.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 8ebb10d44de7..51a613f477a9 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -138,22 +138,26 @@ EXPORT_SYMBOL(__folio_put);
  */
 void put_pages_list(struct list_head *pages)
 {
-	struct folio *folio, *next;
+	struct folio_batch fbatch;
+	struct folio *folio;
 
-	list_for_each_entry_safe(folio, next, pages, lru) {
-		if (!folio_put_testzero(folio)) {
-			list_del(&folio->lru);
+	folio_batch_init(&fbatch);
+	list_for_each_entry(folio, pages, lru) {
+		if (!folio_put_testzero(folio))
 			continue;
-		}
 		if (folio_test_large(folio)) {
-			list_del(&folio->lru);
 			__folio_put_large(folio);
 			continue;
 		}
 		/* LRU flag must be clear because it's passed using the lru */
+		if (folio_batch_add(&fbatch, folio) > 0)
+			continue;
+		free_unref_folios(&fbatch);
+		fbatch.nr = 0;
 	}
 
-	free_unref_page_list(pages);
+	if (fbatch.nr)
+		free_unref_folios(&fbatch);
 	INIT_LIST_HEAD(pages);
 }
 EXPORT_SYMBOL(put_pages_list);
-- 
2.40.1