Re: cpu stall and hyperthread

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I can quite reliably trigger this cpu stall error now. Just try to start several KVM guests.

It seems the kvm progress uses too much CPU?

Since ps -efl showed that the priority of the kvm kernel thread was -20. So I tried,

CONFIG_RCU_BOOST=y
CONFIG_RCU_BOOST_PRIO=50
CONFIG_RCU_BOOST_DELAY=500

But I still got the same error :(

Are there any way I can use to narrow down this error?

Is it possible to non-preemptible RCU in PREEMPT_RT kernel? I know it will reduce the system's RT performance, but we can make sure the reason of this cpu stall error is the preemptible RCU

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)

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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