From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 42310900137 for ; Thu, 28 Jul 2011 04:13:12 -0400 (EDT) Subject: [patch 3/3]vmscan: cleanup kswapd_try_to_sleep From: Shaohua Li Content-Type: text/plain; charset="UTF-8" Date: Thu, 28 Jul 2011 16:13:09 +0800 Message-ID: <1311840789.15392.409.camel@sli10-conroe> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm , mgorman@suse.de, Minchan Kim 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 --- 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); } /* -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org