vmscan: factor out kswapd sleeping logic from kswapd()
Currently, kswapd() has deep nesting and is slightly hard to read. Clean
this up.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 86f8c34..cacdf66 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2371,6 +2371,50 @@
return sc.nr_reclaimed;
}
+static void kswapd_try_to_sleep(pg_data_t *pgdat, int order)
+{
+ long remaining = 0;
+ DEFINE_WAIT(wait);
+
+ if (freezing(current) || kthread_should_stop())
+ return;
+
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
+
+ /* Try to sleep for a short interval */
+ if (!sleeping_prematurely(pgdat, 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(pgdat, order, remaining)) {
+ trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
+
+ /*
+ * vmstat counters are not perfectly accurate and the estimated
+ * value for counters such as NR_FREE_PAGES can deviate from the
+ * true value by nr_online_cpus * threshold. To avoid the zone
+ * watermarks being breached while under pressure, we reduce the
+ * per-cpu vmstat threshold while kswapd is awake and restore
+ * them before going back to sleep.
+ */
+ set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
+ schedule();
+ set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
+ } else {
+ if (remaining)
+ count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
+ else
+ count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
+ }
+ finish_wait(&pgdat->kswapd_wait, &wait);
+}
+
/*
* The background pageout daemon, started as a kernel thread
* from the init process.
@@ -2389,7 +2433,7 @@
unsigned long order;
pg_data_t *pgdat = (pg_data_t*)p;
struct task_struct *tsk = current;
- DEFINE_WAIT(wait);
+
struct reclaim_state reclaim_state = {
.reclaimed_slab = 0,
};
@@ -2421,7 +2465,6 @@
unsigned long new_order;
int ret;
- prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
new_order = pgdat->kswapd_max_order;
pgdat->kswapd_max_order = 0;
if (order < new_order) {
@@ -2431,52 +2474,9 @@
*/
order = new_order;
} else {
- if (!freezing(current) && !kthread_should_stop()) {
- long remaining = 0;
-
- /* Try to sleep for a short interval */
- if (!sleeping_prematurely(pgdat, 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(pgdat, order, remaining)) {
- trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
-
- /*
- * vmstat counters are not perfectly
- * accurate and the estimated value
- * for counters such as NR_FREE_PAGES
- * can deviate from the true value by
- * nr_online_cpus * threshold. To
- * avoid the zone watermarks being
- * breached while under pressure, we
- * reduce the per-cpu vmstat threshold
- * while kswapd is awake and restore
- * them before going back to sleep.
- */
- set_pgdat_percpu_threshold(pgdat,
- calculate_normal_threshold);
- schedule();
- set_pgdat_percpu_threshold(pgdat,
- calculate_pressure_threshold);
- } else {
- if (remaining)
- count_vm_event(KSWAPD_LOW_WMARK_HIT_QUICKLY);
- else
- count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
- }
- }
-
+ kswapd_try_to_sleep(pgdat, order);
order = pgdat->kswapd_max_order;
}
- finish_wait(&pgdat->kswapd_wait, &wait);
ret = try_to_freeze();
if (kthread_should_stop())