Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751807Ab1EMEQJ (ORCPT ); Fri, 13 May 2011 00:16:09 -0400 Received: from mail-qw0-f46.google.com ([209.85.216.46]:43518 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751052Ab1EMEQF convert rfc822-to-8bit (ORCPT ); Fri, 13 May 2011 00:16:05 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=LHCrlrNn9FYgDgVZYsy7ofd4px7VRGMuz2unDGouw4cg0hXuqfzrPRieCu7lx1FpH7 v0GH+XDMRm0YgJu+mti3XWDY2MdYjm0x4bLFH4KufhJ8dbK8IaZ1ots7L97GLREzHNGz Om1XzA+4dspSWDHvfSRHXuGeft1IJiLd5Tcj8= MIME-Version: 1.0 In-Reply-To: References: <1889981320.330808.1305081044822.JavaMail.root@zmail06.collab.prod.int.phx2.redhat.com> Date: Fri, 13 May 2011 13:16:02 +0900 Message-ID: Subject: Re: OOM Killer don't works at all if the system have >gigabytes memory (was Re: [PATCH] mm: check zone->all_unreclaimable in all_unreclaimable()) From: Minchan Kim To: David Rientjes Cc: CAI Qian , KOSAKI Motohiro , avagin@gmail.com, Andrey Vagin , Andrew Morton , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hugh Dickins , Oleg Nesterov Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5838 Lines: 136 On Fri, May 13, 2011 at 4:38 AM, David Rientjes wrote: > On Thu, 12 May 2011, Minchan Kim wrote: > >> > processes a 1% bonus for every 30% of memory they use as proposed >> > earlier.) >> >> I didn't follow earlier your suggestion. >> But it's not formal patch so I expect if you send formal patch to >> merge, you would write down the rationale. >> > > Yes, I'm sure we'll still have additional discussion when KOSAKI-san > replies to my review of his patchset, so this quick patch was written only > for CAI's testing at this point. > > In reference to the above, I think that giving root processes a 3% bonus > at all times may be a bit aggressive.  As mentioned before, I don't think > that all root processes using 4% of memory and the remainder of system > threads are using 1% should all be considered equal.  At the same time, I > do not believe that two threads using 50% of memory should be considered > equal if one is root and one is not.  So my idea was to discount 1% for > every 30% of memory that a root process uses rather than a strict 3%. > > That change can be debated and I think we'll probably settle on something > more aggressive like 1% for every 10% of memory used since oom scores are > only useful in comparison to other oom scores: in the above scenario where > there are two threads, one by root and one not by root, using 50% of > memory each, I think it would be legitimate to give the root task a 5% > bonus so that it would only be selected if no other threads used more than > 44% of memory (even though the root thread is truly using 50%). > > This is a heuristic within the oom killer badness scoring that can always > be debated back and forth, but I think a 1% bonus for root processes for > every 10% of memory used is plausible. > > Comments? Yes. Tend to agree. Apparently, absolute 3% bonus is a problem in CAI's case. Your approach which makes bonus with function of rss is consistent with current OOM heuristic. So In consistency POV, I like it as it could help deterministic OOM policy. About 30% or 10% things, I think it's hard to define a ideal magic value for handling for whole workloads. It would be very arguable. So we might need some standard method to measure it/or redhat/suse peoples. Anyway, I don't want to argue it until we get a number. > >> > diff --git a/mm/oom_kill.c b/mm/oom_kill.c >> > --- a/mm/oom_kill.c >> > +++ b/mm/oom_kill.c >> > @@ -160,7 +160,7 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, >> >         */ >> >        if (p->flags & PF_OOM_ORIGIN) { >> >                task_unlock(p); >> > -               return 1000; >> > +               return 10000; >> >        } >> > >> >        /* >> > @@ -177,32 +177,32 @@ unsigned int oom_badness(struct task_struct *p, struct mem_cgroup *mem, >> >        points = get_mm_rss(p->mm) + p->mm->nr_ptes; >> >        points += get_mm_counter(p->mm, MM_SWAPENTS); >> > >> > -       points *= 1000; >> > +       points *= 10000; >> >        points /= totalpages; >> >        task_unlock(p); >> > >> >        /* >> > -        * Root processes get 3% bonus, just like the __vm_enough_memory() >> > -        * implementation used by LSMs. >> > +        * Root processes get 1% bonus per 30% memory used for a total of 3% >> > +        * possible just like LSMs. >> >         */ >> >        if (has_capability_noaudit(p, CAP_SYS_ADMIN)) >> > -               points -= 30; >> > +               points -= 100 * (points / 3000); >> > >> >        /* >> >         * /proc/pid/oom_score_adj ranges from -1000 to +1000 such that it may >> >         * either completely disable oom killing or always prefer a certain >> >         * task. >> >         */ >> > -       points += p->signal->oom_score_adj; >> > +       points += p->signal->oom_score_adj * 10; >> > >> >        /* >> >         * Never return 0 for an eligible task that may be killed since it's >> > -        * possible that no single user task uses more than 0.1% of memory and >> > +        * possible that no single user task uses more than 0.01% of memory and >> >         * no single admin tasks uses more than 3.0%. >> >         */ >> >        if (points <= 0) >> >                return 1; >> > -       return (points < 1000) ? points : 1000; >> > +       return (points < 10000) ? points : 10000; >> >  } >> > >> >  /* >> > @@ -314,7 +314,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, >> >                         */ >> >                        if (p == current) { >> >                                chosen = p; >> > -                               *ppoints = 1000; >> > +                               *ppoints = 10000; >> >> Scattering constant value isn't good. >> You are proving it now. >> I think you did it since this is not a formal patch. >> I expect you will define new value (ex, OOM_INTERNAL_MAX_SCORE or whatever) >> > > Right, we could probably do something like > >        #define OOM_SCORE_MAX_FACTOR    10 >        #define OOM_SCORE_MAX           (OOM_SCORE_ADJ_MAX * OOM_SCORE_MAX_FACTOR) > > in mm/oom_kill.c, which would then be used to replace all of the constants > above since OOM_SCORE_ADJ_MAX is already defined to be 1000 in > include/linux/oom.h. Looks good to me. Let's wait KOSAKI's opinion and CAI's test result. -- 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/