We expect a file page access after dropping caches should be a major
fault, but sometimes it's still a minor fault. That's because a file
page can't be dropped if it's in a per-cpu pagevec. Draining all pages
from per-cpu pagevec to lru list before trying to drop caches.
Signed-off-by: Andrew Yang <andrew.yang@xxxxxxxxxxxx>
---
fs/drop_caches.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index e619c31b6bd9..b9575957a7c2 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -10,6 +10,7 @@
#include <linux/writeback.h>
#include <linux/sysctl.h>
#include <linux/gfp.h>
+#include <linux/swap.h>
#include "internal.h"
/* A global variable is a bit ugly, but it keeps the code simple */
@@ -59,6 +60,7 @@ int drop_caches_sysctl_handler(struct ctl_table *table, int write,
static int stfu;
if (sysctl_drop_caches & 1) {
+ lru_add_drain_all();
iterate_supers(drop_pagecache_sb, NULL);
count_vm_event(DROP_PAGECACHE);
}
--
2.18.0
