The page reclamation scanner tries to keep executable pages resident,
since taking a hard page fault to satisfy an icache miss is really not
great for interactivity. Anonymous executable pages tend to contain
code that has been just-in-time compiled for performance reasons. By
requiring that executable pages be file-backed, we're putting possibly
the most performance-sensitive code at higher risk of eviction, which
seems backwards.
On an amd64 machine running Fedora 31, the firefox I happen to have
running requires about 89M of file-backed text and 12M of anonymous text
for 30 open tabs. The next largest process in terms of anonymous text is
gnome-shell, with 1M anonymous and 57M file-backed. No other process had
significant anonymous text, most had none. Penalizing those 13M
specifically when under memory pressure seems like an easy hazard to
avoid.
Signed-off-by: Adam Jackson <ajax@xxxxxxxxxx>
---
mm/vmscan.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ee4eecc7e1c2..9bfbc30d61d8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2095,15 +2095,12 @@ static void shrink_active_list(unsigned long nr_to_scan,
&vm_flags)) {
nr_rotated += hpage_nr_pages(page);
/*
- * Identify referenced, file-backed active pages and
- * give them one more trip around the active list. So
+ * Identify referenced, executable active pages and
+ * give them one more trip around the active list, so
* that executable code get better chances to stay in
- * memory under moderate memory pressure. Anon pages
- * are not likely to be evicted by use-once streaming
- * IO, plus JVM can create lots of anon VM_EXEC pages,
- * so we ignore them here.
+ * memory under moderate memory pressure.
*/
- if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
+ if ((vm_flags & VM_EXEC)) {
list_add(&page->lru, &l_active);
continue;
}
--
2.23.0
