The quilt patch titled
Subject: mm: vmscan: avoid split during shrink_folio_list()
has been removed from the -mm tree. Its filename was
mm-vmscan-avoid-split-during-shrink_folio_list.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Ryan Roberts <ryan.roberts@xxxxxxx>
Subject: mm: vmscan: avoid split during shrink_folio_list()
Date: Mon, 8 Apr 2024 19:39:45 +0100
Now that swap supports storing all mTHP sizes, avoid splitting large
folios before swap-out. This benefits performance of the swap-out path by
eliding split_folio_to_list(), which is expensive, and also sets us up for
swapping in large folios in a future series.
If the folio is partially mapped, we continue to split it since we want to
avoid the extra IO overhead and storage of writing out pages
uneccessarily.
THP_SWPOUT and THP_SWPOUT_FALLBACK counters should continue to count
events only for PMD-mappable folios to avoid user confusion. THP_SWPOUT
already has the appropriate guard. Add a guard for THP_SWPOUT_FALLBACK.
It may be appropriate to add per-size counters in future.
Link: https://lkml.kernel.org/r/20240408183946.2991168-7-ryan.roberts@xxxxxxx
Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Barry Song <v-songbaohua@xxxxxxxx>
Cc: Barry Song <21cnbao@xxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: Gao Xiang <xiang@xxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Lance Yang <ioworker0@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
--- a/mm/vmscan.c~mm-vmscan-avoid-split-during-shrink_folio_list
+++ a/mm/vmscan.c
@@ -1206,25 +1206,25 @@ retry:
if (!can_split_folio(folio, NULL))
goto activate_locked;
/*
- * Split folios without a PMD map right
- * away. Chances are some or all of the
- * tail pages can be freed without IO.
+ * Split partially mapped folios right away.
+ * We can free the unmapped pages without IO.
*/
- if (!folio_entire_mapcount(folio) &&
- split_folio_to_list(folio,
- folio_list))
+ if (data_race(!list_empty(&folio->_deferred_list)) &&
+ split_folio_to_list(folio, folio_list))
goto activate_locked;
}
if (!add_to_swap(folio)) {
if (!folio_test_large(folio))
goto activate_locked_split;
/* Fallback to swap normal pages */
- if (split_folio_to_list(folio,
- folio_list))
+ if (split_folio_to_list(folio, folio_list))
goto activate_locked;
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- count_memcg_folio_events(folio, THP_SWPOUT_FALLBACK, 1);
- count_vm_event(THP_SWPOUT_FALLBACK);
+ if (nr_pages >= HPAGE_PMD_NR) {
+ count_memcg_folio_events(folio,
+ THP_SWPOUT_FALLBACK, 1);
+ count_vm_event(THP_SWPOUT_FALLBACK);
+ }
#endif
if (!add_to_swap(folio))
goto activate_locked_split;
_
Patches currently in -mm which might be from ryan.roberts@xxxxxxx are
selftests-mm-soft-dirty-should-fail-if-a-testcase-fails.patch
mm-fix-race-between-__split_huge_pmd_locked-and-gup-fast.patch
