Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752067Ab1ELA7a (ORCPT ); Wed, 11 May 2011 20:59:30 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:47869 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751360Ab1ELA72 (ORCPT ); Wed, 11 May 2011 20:59:28 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 12 May 2011 09:52:43 +0900 From: KAMEZAWA Hiroyuki 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 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> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.1.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2782 Lines: 82 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 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/