From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Dong Liu <dliu.cn@gmail.com>
Cc: linux-rt-users@vger.kernel.org
Subject: Re: cpu stall and hyperthread
Date: Tue, 3 Jul 2012 18:13:00 -0700 [thread overview]
Message-ID: <20120704011300.GA2522@linux.vnet.ibm.com> (raw)
In-Reply-To: <4FF351C6.3000100@gmail.com>
On Tue, Jul 03, 2012 at 04:10:46PM -0400, Dong Liu wrote:
> Hi,
>
> After reading the RCU cpu stall doc. I thought that CONFIG_NO_HZ
> might have something to do with this problem. And I think the NO_HZ
> config is not good for RT performance, so I made a new kernel
> without NO_HZ. It lasted longer but eventually cpu stalls happened
> again.
>
> I then disable the cpu stall checking by set
>
> /sys/module/rcutree/parameters/rcu_cpu_stall_suppress
>
> to "1", but it did not solve the problem. Instead of cpu stall I had
>
> BUG: soft lockup - CPU#0 stuck for 279s! [swapper/0:0]
>
> And even I disabled Hyper-Threading, I also got cpu stall now.
>
> CPU stalls also occurred in KVM guest OS as well.
>
> But I never get cpu stall when I'm running the normal kernel without
> -rt patch.
>
> Is the cpu stall a known issue with the rt patch?
>
> Thanks,
>
> Dong
>
> On 6/27/12 11:22 PM, Dong Liu wrote:
> >Hi,
> >
> >I'm running 3.4.3-rt11 and 3.2.18-rt29 on a system with Intel I7 860, I
> >noticed that with hyperthread enabled, I'm getting kernel error
> >
> >rcu_preempt detected stalls on CPUs/tasks: { 3} (detected by 5, t=60002
> >jiffies)
Did you get stack traces with this error? And did you get repeated
stall messages if you waited a few minutes after the first one?
If so, the stack traces can help track down the problem.
Thanx, Paul
> >But with hyperthread disabled, no such error.
> >
> >Is preempt_rt not supposed to be used with hyperthread?
> >
> >Thanks,
> >
> >Dong
> >
> >P.S.
>
> --
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>
next prev parent reply other threads:[~2012-07-04 1:19 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4FEBCDDE.60503@gmail.com>
2012-07-03 20:10 ` cpu stall and hyperthread Dong Liu
2012-07-04 1:13 ` Paul E. McKenney [this message]
2012-07-04 17:27 ` Dong Liu
2012-07-04 22:52 ` Carsten Emde
2012-07-05 18:41 ` Dong Liu
2012-07-05 22:48 ` Carsten Emde
2012-07-06 6:07 ` Dong Liu
2012-07-05 23:02 ` Carsten Emde
2012-07-06 6:04 ` Dong Liu
2012-07-05 18:48 ` Dong Liu
2012-07-06 6:20 ` Dong Liu
2012-07-06 11:40 ` Carsten Emde
2012-07-06 16:03 ` Dong Liu
2012-07-06 21:01 ` Carsten Emde
2012-07-09 4:33 ` Dong Liu
2012-07-09 6:53 ` Carsten Emde
2012-07-09 14:46 ` Dong Liu
2012-07-06 15:58 ` Dong Liu
2012-07-06 17:32 ` Dong Liu
2012-07-12 20:27 ` Dong Liu
2012-06-28 3:23 Dong Liu
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