cleanup kswapd_try_to_sleep() a little bit. Sometimes kswapd doesn't
really sleep. In such case, don't call prepare_to_wait/finish_wait.
It just wastes CPU.
Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---
mm/vmscan.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
Index: linux/mm/vmscan.c
===================================================================
--- linux.orig/mm/vmscan.c 2011-07-28 15:52:35.000000000 +0800
+++ linux/mm/vmscan.c 2011-07-28 15:55:56.000000000 +0800
@@ -2709,13 +2709,11 @@ static void kswapd_try_to_sleep(pg_data_
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, classzone_idx)) {
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
remaining = schedule_timeout(HZ/10);
finish_wait(&pgdat->kswapd_wait, &wait);
- prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
}
/*
@@ -2734,7 +2732,9 @@ static void kswapd_try_to_sleep(pg_data_
* them before going back to sleep.
*/
set_pgdat_percpu_threshold(pgdat, calculate_normal_threshold);
+ prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
schedule();
+ finish_wait(&pgdat->kswapd_wait, &wait);
set_pgdat_percpu_threshold(pgdat, calculate_pressure_threshold);
} else {
if (remaining)
@@ -2742,7 +2742,6 @@ static void kswapd_try_to_sleep(pg_data_
else
count_vm_event(KSWAPD_HIGH_WMARK_HIT_QUICKLY);
}
- finish_wait(&pgdat->kswapd_wait, &wait);
}
/*
--
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