When a lot of streaming file IO is happening, it makes sense to
evict just the inactive file pages and leave the other LRU lists
alone.
Likewise, when driving a cgroup hierarchy into its hard limit,
or over its soft limit, it makes sense to pick a child cgroup
that has lots of inactive file pages, and evict those first.
Being over its soft limit is considered a stronger preference
than just having a lot of inactive file pages, so a well behaved
cgroup is allowed to keep its file cache when there is a "badly
behaving" one in the same hierarchy.
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
---
mm/vmscan.c | 37 +++++++++++++++++++++++++++++++++----
1 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 769fdcd..2884b4f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1576,6 +1576,19 @@ static int inactive_list_is_low(struct lruvec *lruvec, enum lru_list lru)
return inactive_anon_is_low(lruvec);
}
+/* If this lruvec has lots of inactive file pages, reclaim those only. */
+static bool reclaim_file_only(struct lruvec *lruvec, struct scan_control *sc,
+ unsigned long anon, unsigned long file)
+{
+ if (inactive_file_is_low(lruvec))
+ return false;
+
+ if (file > (anon + file) >> sc->priority)
+ return true;
+
+ return false;
+}
+
static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
struct lruvec *lruvec, struct scan_control *sc)
{
@@ -1658,6 +1671,14 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
}
}
+ /* Lots of inactive file pages? Reclaim those only. */
+ if (reclaim_file_only(lruvec, sc, anon, file)) {
+ fraction[0] = 0;
+ fraction[1] = 1;
+ denominator = 1;
+ goto out;
+ }
+
/*
* With swappiness at 100, anonymous and file have the same priority.
* This scanning priority is essentially the inverse of IO cost.
@@ -1922,8 +1943,8 @@ static void age_recent_pressure(struct lruvec *lruvec, struct zone *zone)
* should always be larger than recent_rotated, and the size should
* always be larger than recent_pressure.
*/
-static u64 reclaim_score(struct mem_cgroup *memcg,
- struct lruvec *lruvec)
+static u64 reclaim_score(struct mem_cgroup *memcg, struct lruvec *lruvec,
+ struct scan_control *sc)
{
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
u64 anon, file;
@@ -1949,6 +1970,14 @@ static u64 reclaim_score(struct mem_cgroup *memcg,
anon *= 10000;
}
+ /*
+ * Prefer reclaiming from an lruvec with lots of inactive file
+ * pages. Once those have been reclaimed, the score will drop so
+ * far we will pick another lruvec to reclaim from.
+ */
+ if (reclaim_file_only(lruvec, sc, anon, file))
+ file *= 100;
+
return max(anon, file);
}
@@ -1977,7 +2006,7 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
age_recent_pressure(lruvec, zone);
- score = reclaim_score(memcg, lruvec);
+ score = reclaim_score(memcg, lruvec, sc);
/* Pick the lruvec with the highest score. */
if (score > max_score) {
@@ -2002,7 +2031,7 @@ static void shrink_zone(struct zone *zone, struct scan_control *sc)
*/
do {
shrink_lruvec(victim_lruvec, sc);
- score = reclaim_score(memcg, victim_lruvec);
+ score = reclaim_score(memcg, victim_lruvec, sc);
} while (sc->nr_to_reclaim > 0 && score > max_score / 2);
mem_cgroup_put(victim_memcg);
--
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