Messages in this thread | | | Date | Fri, 13 May 2011 13:16:02 +0900 | 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 <> |
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On Fri, May 13, 2011 at 4:38 AM, David Rientjes <rientjes@google.com> 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/
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