From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id A43846B01C4 for ; Mon, 31 May 2010 06:33:34 -0400 (EDT) Received: by ywh17 with SMTP id 17so784076ywh.1 for ; Mon, 31 May 2010 03:33:33 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20100531155102.9a122772.kamezawa.hiroyu@jp.fujitsu.com> 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> <20100531155102.9a122772.kamezawa.hiroyu@jp.fujitsu.com> Date: Mon, 31 May 2010 19:33:32 +0900 Message-ID: Subject: Re: [RFC] oom-kill: give the dying task a higher priority From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki 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, May 31, 2010 at 3:51 PM, KAMEZAWA Hiroyuki wrote: > 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 qui= ckly and die, >> >> >> >> freeing needed memory. >> >> >> >> >> >> >> >> Signed-off-by: Luis Claudio R. Gon=C3=A7alves >> >> >> >> >> >> >> >> 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_proce= ss(unsigned long *ppoints) >> >> >> >> =C2=A0 */ >> >> >> >> =C2=A0static void __oom_kill_task(struct task_struct *p, int ve= rbose) >> >> >> >> =C2=A0{ >> >> >> >> + =C2=A0 =C2=A0 struct sched_param param; >> >> >> >> + >> >> >> >> =C2=A0 =C2=A0 =C2=A0 if (is_global_init(p)) { >> >> >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WARN_ON(1); >> >> >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 printk(KERN_WA= RNING "tried to kill init!\n"); >> >> >> >> @@ -288,6 +290,8 @@ static void __oom_kill_task(struct task_str= uct *p, int verbose) >> >> >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0* exit() and clear out its resources= quickly... >> >> >> >> =C2=A0 =C2=A0 =C2=A0 =C2=A0*/ >> >> >> >> =C2=A0 =C2=A0 =C2=A0 p->time_slice =3D HZ; >> >> >> >> + =C2=A0 =C2=A0 param.sched_priority =3D MAX_RT_PRIO-10; >> >> >> >> + =C2=A0 =C2=A0 sched_setscheduler(p, SCHED_FIFO, ¶m); >> >> >> >> =C2=A0 =C2=A0 =C2=A0 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 whic= h 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 =C2=A0KILL signal, the process i= nclude >> >> the thread will be killed. >> >> >> > yes, so, if you want a _process_ die quickly, you have to acceralte th= e whole >> > threads on a process. Acceralating a thread in a process is not big he= lp. >> >> 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 =C2=A0CONSTRAINT_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 agai= nst 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. I= f 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 see= ms overkill" > is given in changelog or comment, it's ok to me. Okay. I got your point. Kame's concern is proper. Couldn't we raise priorities of whole threads of the task killed? > > Thanks, > -Kame > > --=20 Kind regards, Minchan Kim -- 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