From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 14BB690016F for ; Wed, 22 Jun 2011 06:47:54 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id C746B3EE0B5 for ; Wed, 22 Jun 2011 19:47:50 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id AE7B445DE61 for ; Wed, 22 Jun 2011 19:47:50 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 982BD45DE4D for ; Wed, 22 Jun 2011 19:47:50 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 8B8581DB8038 for ; Wed, 22 Jun 2011 19:47:50 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 547C31DB802C for ; Wed, 22 Jun 2011 19:47:50 +0900 (JST) Message-ID: <4E01C84A.60400@jp.fujitsu.com> Date: Wed, 22 Jun 2011 19:47:38 +0900 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: [PATCH 3/6] oom: kill younger process first References: <4E01C7D5.3060603@jp.fujitsu.com> In-Reply-To: <4E01C7D5.3060603@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: kosaki.motohiro@jp.fujitsu.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, caiqian@redhat.com, rientjes@google.com, hughd@google.com, kamezawa.hiroyu@jp.fujitsu.com, minchan.kim@gmail.com, oleg@redhat.com This patch introduces do_each_thread_reverse() and select_bad_process() uses it. The benefits are two, 1) oom-killer can kill younger process than older if they have a same oom score. Usually younger process is less important. 2) younger task often have PF_EXITING because shell script makes a lot of short lived processes. Reverse order search can detect it faster. Reported-by: CAI Qian Signed-off-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Acked-by: David Rientjes Cc: KAMEZAWA Hiroyuki --- include/linux/sched.h | 11 +++++++++++ mm/oom_kill.c | 2 +- 2 files changed, 12 insertions(+), 1 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index e4e6d7b..392ff30 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2257,6 +2257,9 @@ static inline unsigned long wait_task_inactive(struct task_struct *p, #define next_task(p) \ list_entry_rcu((p)->tasks.next, struct task_struct, tasks) +#define prev_task(p) \ + list_entry((p)->tasks.prev, struct task_struct, tasks) + #define for_each_process(p) \ for (p = &init_task ; (p = next_task(p)) != &init_task ; ) @@ -2269,6 +2272,14 @@ extern bool current_is_single_threaded(void); #define do_each_thread(g, t) \ for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do +/* + * Similar to do_each_thread(). but two difference are there. + * - traverse tasks reverse order (i.e. younger to older) + * - caller must hold tasklist_lock. rcu_read_lock isn't enough +*/ +#define do_each_thread_reverse(g, t) \ + for (g = t = &init_task ; (g = t = prev_task(g)) != &init_task ; ) do + #define while_each_thread(g, t) \ while ((t = next_thread(t)) != g) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 9412657..797308b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -300,7 +300,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, struct task_struct *chosen = NULL; *ppoints = 0; - do_each_thread(g, p) { + do_each_thread_reverse(g, p) { unsigned int points; if (!p->mm) -- 1.7.3.1 -- 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