aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--mm/vmscan.c36
1 files changed, 25 insertions, 11 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cc29fca8d989..9149444f947d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2064,13 +2064,27 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
unsigned long nr_reclaimed = 0;
unsigned long nr_to_reclaim = sc->nr_to_reclaim;
struct blk_plug plug;
- bool scan_adjusted = false;
+ bool scan_adjusted;
get_scan_count(lruvec, sc, nr);
/* Record the original scan target for proportional adjustments later */
memcpy(targets, nr, sizeof(nr));
+ /*
+ * Global reclaiming within direct reclaim at DEF_PRIORITY is a normal
+ * event that can occur when there is little memory pressure e.g.
+ * multiple streaming readers/writers. Hence, we do not abort scanning
+ * when the requested number of pages are reclaimed when scanning at
+ * DEF_PRIORITY on the assumption that the fact we are direct
+ * reclaiming implies that kswapd is not keeping up and it is best to
+ * do a batch of work at once. For memcg reclaim one check is made to
+ * abort proportional reclaim if either the file or anon lru has already
+ * dropped to zero at the first pass.
+ */
+ scan_adjusted = (global_reclaim(sc) && !current_is_kswapd() &&
+ sc->priority == DEF_PRIORITY);
+
blk_start_plug(&plug);
while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
nr[LRU_INACTIVE_FILE]) {
@@ -2091,17 +2105,8 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
continue;
/*
- * For global direct reclaim, reclaim only the number of pages
- * requested. Less care is taken to scan proportionally as it
- * is more important to minimise direct reclaim stall latency
- * than it is to properly age the LRU lists.
- */
- if (global_reclaim(sc) && !current_is_kswapd())
- break;
-
- /*
* For kswapd and memcg, reclaim at least the number of pages
- * requested. Ensure that the anon and file LRUs shrink
+ * requested. Ensure that the anon and file LRUs are scanned
* proportionally what was requested by get_scan_count(). We
* stop reclaiming one LRU and reduce the amount scanning
* proportional to the original scan target.
@@ -2109,6 +2114,15 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
nr_file = nr[LRU_INACTIVE_FILE] + nr[LRU_ACTIVE_FILE];
nr_anon = nr[LRU_INACTIVE_ANON] + nr[LRU_ACTIVE_ANON];
+ /*
+ * It's just vindictive to attack the larger once the smaller
+ * has gone to zero. And given the way we stop scanning the
+ * smaller below, this makes sure that we only make one nudge
+ * towards proportionality once we've got nr_to_reclaim.
+ */
+ if (!nr_file || !nr_anon)
+ break;
+
if (nr_file > nr_anon) {
unsigned long scan_target = targets[LRU_INACTIVE_ANON] +
targets[LRU_ACTIVE_ANON] + 1;