From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 87D1D6B0012 for ; Tue, 10 May 2011 19:31:14 -0400 (EDT) Received: from wpaz5.hot.corp.google.com (wpaz5.hot.corp.google.com [172.24.198.69]) by smtp-out.google.com with ESMTP id p4ANVCQq027216 for ; Tue, 10 May 2011 16:31:12 -0700 Received: from pxi10 (pxi10.prod.google.com [10.243.27.10]) by wpaz5.hot.corp.google.com with ESMTP id p4ANVAEG030294 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Tue, 10 May 2011 16:31:11 -0700 Received: by pxi10 with SMTP id 10so5095956pxi.22 for ; Tue, 10 May 2011 16:31:10 -0700 (PDT) Date: Tue, 10 May 2011 16:31:08 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 2/4] oom: kill younger process first In-Reply-To: <20110510171641.16AF.A69D9226@jp.fujitsu.com> Message-ID: 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 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 , Hugh Dickins , Oleg Nesterov On Tue, 10 May 2011, 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. > I like this change, thanks! I'm suprised we haven't needed a do_each_thread_reverse() in the past somewhere else in the kernel. Could you update the comment about do_each_thread() not being break-safe in the second version, though? After that: Acked-by: David Rientjes > Reported-by: CAI Qian > Signed-off-by: KOSAKI Motohiro > --- > 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) -- 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