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 ESMTP id 920B36B0012 for ; Wed, 11 May 2011 20:59:30 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 747C93EE0C1 for ; Thu, 12 May 2011 09:59:26 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 5958145DE61 for ; Thu, 12 May 2011 09:59:26 +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 3675545DD74 for ; Thu, 12 May 2011 09:59:26 +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 29D181DB803F for ; Thu, 12 May 2011 09:59:26 +0900 (JST) Received: from m107.s.css.fujitsu.com (m107.s.css.fujitsu.com [10.240.81.147]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id D78C21DB802C for ; Thu, 12 May 2011 09:59:25 +0900 (JST) Date: Thu, 12 May 2011 09:52:43 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 2/4] oom: kill younger process first Message-Id: <20110512095243.c57e3e83.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110510171641.16AF.A69D9226@jp.fujitsu.com> References: <20110509182110.167F.A69D9226@jp.fujitsu.com> <20110510171335.16A7.A69D9226@jp.fujitsu.com> <20110510171641.16AF.A69D9226@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: CAI Qian , avagin@gmail.com, Andrey Vagin , Andrew Morton , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Minchan Kim , David Rientjes , Hugh Dickins , Oleg Nesterov On Tue, 10 May 2011 17:15:01 +0900 (JST) KOSAKI Motohiro wrote: > 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 IIUC, for_each_thread() can be called under rcu_read_lock() but for_each_thread_reverse() must be under tasklist_lock. Could you add some comment ? and prev_task() should use list_entry() not list_entry_rcu(). Thanks, -Kame > --- > include/linux/sched.h | 6 ++++++ > mm/oom_kill.c | 2 +- > 2 files changed, 7 insertions(+), 1 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 013314a..a0a8339 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2194,6 +2194,9 @@ 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_rcu((p)->tasks.prev, struct task_struct, tasks) > + > #define for_each_process(p) \ > for (p = &init_task ; (p = next_task(p)) != &init_task ; ) > > @@ -2206,6 +2209,9 @@ 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 > > +#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 118d958..0cf5091 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -282,7 +282,7 @@ 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 from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- 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