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-rw-r--r--include/linux/vmstat.h1
-rw-r--r--mm/vmscan.c44
-rw-r--r--mm/vmstat.c2
3 files changed, 45 insertions, 2 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index d85889710f9b..fd5be240c0b7 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -40,6 +40,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
PGSCAN_ZONE_RECLAIM_FAILED,
#endif
PGINODESTEAL, SLABS_SCANNED, KSWAPD_STEAL, KSWAPD_INODESTEAL,
+ KSWAPD_PREMATURE_FAST, KSWAPD_PREMATURE_SLOW,
PAGEOUTRUN, ALLOCSTALL, PGROTATED,
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 61d3a9a0d96f..e176bd3936da 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1904,6 +1904,24 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem_cont,
}
#endif
+/* is kswapd sleeping prematurely? */
+static int sleeping_prematurely(int order, long remaining)
+{
+ struct zone *zone;
+
+ /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
+ if (remaining)
+ return 1;
+
+ /* If after HZ/10, a zone is below the high mark, it's premature */
+ for_each_populated_zone(zone)
+ if (!zone_watermark_ok(zone, order, high_wmark_pages(zone),
+ 0, 0))
+ return 1;
+
+ return 0;
+}
+
/*
* For kswapd, balance_pgdat() will work across all this node's zones until
* they are all at high_wmark_pages(zone).
@@ -2185,8 +2203,30 @@ static int kswapd(void *p)
*/
order = new_order;
} else {
- if (!freezing(current) && !kthread_should_stop())
- schedule();
+ if (!freezing(current) && !kthread_should_stop()) {
+ long remaining = 0;
+
+ /* Try to sleep for a short interval */
+ if (!sleeping_prematurely(order, remaining)) {
+ remaining = schedule_timeout(HZ/10);
+ finish_wait(&pgdat->kswapd_wait, &wait);
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+ }
+
+ /*
+ * After a short sleep, check if it was a
+ * premature sleep. If not, then go fully
+ * to sleep until explicitly woken up
+ */
+ if (!sleeping_prematurely(order, remaining))
+ schedule();
+ else {
+ if (remaining)
+ count_vm_event(KSWAPD_PREMATURE_FAST);
+ else
+ count_vm_event(KSWAPD_PREMATURE_SLOW);
+ }
+ }
order = pgdat->kswapd_max_order;
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index dad2327e4580..63ab71455c5b 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -683,6 +683,8 @@ static const char * const vmstat_text[] = {
"slabs_scanned",
"kswapd_steal",
"kswapd_inodesteal",
+ "kswapd_slept_prematurely_fast",
+ "kswapd_slept_prematurely_slow",
"pageoutrun",
"allocstall",