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 SMTP id 4A3066B01C1 for ; Mon, 31 May 2010 02:55:23 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o4V6tK1W019383 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Mon, 31 May 2010 15:55:21 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 7875C45DE70 for ; Mon, 31 May 2010 15:55:20 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 4FA8245DE6F for ; Mon, 31 May 2010 15:55:20 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 2D12AE38002 for ; Mon, 31 May 2010 15:55:20 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id CB3BE1DB8037 for ; Mon, 31 May 2010 15:55:19 +0900 (JST) Date: Mon, 31 May 2010 15:51:02 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC] oom-kill: give the dying task a higher priority Message-Id: <20100531155102.9a122772.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20100528143605.7E2A.A69D9226@jp.fujitsu.com> <20100528145329.7E2D.A69D9226@jp.fujitsu.com> <20100528125305.GE11364@uudg.org> <20100528140623.GA11041@barrios-desktop> <20100528143617.GF11364@uudg.org> <20100528151249.GB12035@barrios-desktop> <20100528152842.GH11364@uudg.org> <20100528154549.GC12035@barrios-desktop> <20100528164826.GJ11364@uudg.org> <20100531092133.73705339.kamezawa.hiroyu@jp.fujitsu.com> <20100531140443.b36a4f02.kamezawa.hiroyu@jp.fujitsu.com> <20100531145415.5e53f837.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: "Luis Claudio R. Goncalves" , KOSAKI Motohiro , balbir@linux.vnet.ibm.com, Oleg Nesterov , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thomas Gleixner , Peter Zijlstra , David Rientjes , Mel Gorman , williams@redhat.com List-ID: On Mon, 31 May 2010 15:09:41 +0900 Minchan Kim wrote: > On Mon, May 31, 2010 at 2:54 PM, KAMEZAWA Hiroyuki > wrote: > > On Mon, 31 May 2010 14:46:05 +0900 > > Minchan Kim wrote: > > > >> On Mon, May 31, 2010 at 2:04 PM, KAMEZAWA Hiroyuki > >> wrote: > >> > On Mon, 31 May 2010 14:01:03 +0900 > >> > Minchan Kim wrote: > >> > > >> >> Hi, Kame. > >> >> > >> >> On Mon, May 31, 2010 at 9:21 AM, KAMEZAWA Hiroyuki > >> >> wrote: > >> >> > On Fri, 28 May 2010 13:48:26 -0300 > >> >> > "Luis Claudio R. Goncalves" wrote: > >> >> >> > >> >> >> oom-killer: give the dying task rt priority (v3) > >> >> >> > >> >> >> Give the dying task RT priority so that it can be scheduled quickly and die, > >> >> >> freeing needed memory. > >> >> >> > >> >> >> Signed-off-by: Luis Claudio R. GonA?alves > >> >> >> > >> >> >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c > >> >> >> index 84bbba2..2b0204f 100644 > >> >> >> --- a/mm/oom_kill.c > >> >> >> +++ b/mm/oom_kill.c > >> >> >> @@ -266,6 +266,8 @@ static struct task_struct *select_bad_process(unsigned long *ppoints) > >> >> >> A */ > >> >> >> A static void __oom_kill_task(struct task_struct *p, int verbose) > >> >> >> A { > >> >> >> + A A struct sched_param param; > >> >> >> + > >> >> >> A A A if (is_global_init(p)) { > >> >> >> A A A A A A A WARN_ON(1); > >> >> >> A A A A A A A printk(KERN_WARNING "tried to kill init!\n"); > >> >> >> @@ -288,6 +290,8 @@ static void __oom_kill_task(struct task_struct *p, int verbose) > >> >> >> A A A A * exit() and clear out its resources quickly... > >> >> >> A A A A */ > >> >> >> A A A p->time_slice = HZ; > >> >> >> + A A param.sched_priority = MAX_RT_PRIO-10; > >> >> >> + A A sched_setscheduler(p, SCHED_FIFO, ¶m); > >> >> >> A A A set_tsk_thread_flag(p, TIF_MEMDIE); > >> >> >> > >> >> > > >> >> > BTW, how about the other threads which share mm_struct ? > >> >> > >> >> Could you elaborate your intention? :) > >> >> > >> > > >> > IIUC, the purpose of rising priority is to accerate dying thread to exit() > >> > for freeing memory AFAP. But to free memory, exit, all threads which share > >> > mm_struct should exit, too. I'm sorry if I miss something. > >> > >> How do we kill only some thread and what's the benefit of it? > >> I think when if some thread receives A KILL signal, the process include > >> the thread will be killed. > >> > > yes, so, if you want a _process_ die quickly, you have to acceralte the whole > > threads on a process. Acceralating a thread in a process is not big help. > > Yes. > > I see the code. > oom_kill_process is called by > > 1. mem_cgroup_out_of_memory > 2. __out_of_memory > 3. out_of_memory > > > (1,2) calls select_bad_process which select victim task in processes > by do_each_process. > But 3 isn't In case of CONSTRAINT_MEMORY_POLICY, it kills current. > In only the case, couldn't we pass task of process, not one of thread? > Hmm, my point is that priority-acceralation is against a thread, not against a process. So, most of threads in memory-eater will not gain high priority even with this patch and works slowly. I have no objections to this patch. I just want to confirm the purpose. If this patch is for accelating exiting process by SIGKILL, it seems not enough. If an explanation as "acceralating all thread's priority in a process seems overkill" is given in changelog or comment, it's ok to me. Thanks, -Kame -- 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/ . Don't email: email@kvack.org