Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759088Ab0FPPb2 (ORCPT ); Wed, 16 Jun 2010 11:31:28 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:43676 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759009Ab0FPPb1 (ORCPT ); Wed, 16 Jun 2010 11:31:27 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=YEhV4ccf1nUZ8osULZqp5RJ15+1b8+WWnMV5Jn73HEnQSQJ0lch+3zNrzKOwupSNlC vEuVVaN1pO2OXbxdU8N/OeKpGIV7jDoc5xdeBJ3iNfmeD+NKE0ejzhLWJhfcCMMtRHrW 1mNcuFq8RYVL4Esx54bMVKpx9xUiTTr9fUsvM= Date: Thu, 17 Jun 2010 00:31:20 +0900 From: Minchan Kim To: KOSAKI Motohiro Cc: LKML , linux-mm , Andrew Morton , David Rientjes , KAMEZAWA Hiroyuki , "Luis Claudio R. Goncalves" , Oleg Nesterov Subject: Re: [PATCH 9/9] oom: give the dying task a higher priority Message-ID: <20100616153120.GH9278@barrios-desktop> References: <20100616201948.72D7.A69D9226@jp.fujitsu.com> <20100616203517.72EF.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100616203517.72EF.A69D9226@jp.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2834 Lines: 78 On Wed, Jun 16, 2010 at 08:36:29PM +0900, KOSAKI Motohiro wrote: > > From: Luis Claudio R. Goncalves > > In a system under heavy load it was observed that even after the > oom-killer selects a task to die, the task may take a long time to die. > > Right after sending a SIGKILL to the task selected by the oom-killer > this task has it's priority increased so that it can exit() exit soon, > freeing memory. That is accomplished by: > > /* > * We give our sacrificial lamb high priority and access to > * all the memory it needs. That way it should be able to > * exit() and clear out its resources quickly... > */ > p->rt.time_slice = HZ; > set_tsk_thread_flag(p, TIF_MEMDIE); > > It sounds plausible giving the dying task an even higher priority to be > sure it will be scheduled sooner and free the desired memory. It was > suggested on LKML using SCHED_FIFO:1, the lowest RT priority so that > this task won't interfere with any running RT task. > > If the dying task is already an RT task, leave it untouched. > Another good suggestion, implemented here, was to avoid boosting the > dying task priority in case of mem_cgroup OOM. > > Signed-off-by: Luis Claudio R. Goncalves > Cc: Minchan Kim > Signed-off-by: KOSAKI Motohiro > --- > mm/oom_kill.c | 38 +++++++++++++++++++++++++++++++++++--- > 1 files changed, 35 insertions(+), 3 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 7e9942d..1ecfc7a 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -82,6 +82,28 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, > #endif /* CONFIG_NUMA */ > > /* > + * If this is a system OOM (not a memcg OOM) and the task selected to be > + * killed is not already running at high (RT) priorities, speed up the > + * recovery by boosting the dying task to the lowest FIFO priority. > + * That helps with the recovery and avoids interfering with RT tasks. > + */ > +static void boost_dying_task_prio(struct task_struct *p, > + struct mem_cgroup *mem) > +{ > + struct sched_param param = { .sched_priority = 1 }; > + > + if (mem) > + return; > + > + if (rt_task(p)) { > + p->rt.time_slice = HZ; > + return; I have a question from long time ago. If we change rt.time_slice _without_ setscheduler, is it effective? I mean scheduler pick up the task faster than other normal task? > + } > + > + sched_setscheduler_nocheck(p, SCHED_FIFO, ¶m); > +} > + > +/* -- Kind regards, Minchan Kim -- 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/