From: John Stultz <johnstul@us.ibm.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Avi Kivity <avi@redhat.com>,
paulmck@linux.vnet.ibm.com,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
mingo@kernel.org, a.p.zijlstra@chello.nl, prarit@redhat.com,
tglx@linutronix.de
Subject: Re: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6
Date: Mon, 06 Aug 2012 11:20:31 -0700 [thread overview]
Message-ID: <50200AEF.5080904@us.ibm.com> (raw)
In-Reply-To: <501FFD2A.4010905@us.ibm.com>
On 08/06/2012 10:21 AM, John Stultz wrote:
> On 08/05/2012 09:55 AM, Sasha Levin wrote:
>> On 07/30/2012 03:17 PM, Avi Kivity wrote:
>>> Possible causes:
>>> - the APIC calibration in the guest failed, so it is programming too
>>> low values into the timer
>>> - it actually needs 1 us wakeups and then can't keep up (esp. as kvm
>>> interrupt injection is slowing it down)
>>>
>>> You can try to find out by changing
>>> arch/x86/kvm/lapic.c:start_lapic_timer() to impose a minimum wakeup of
>>> (say) 20 microseconds which will let the guest live long enough for you
>>> to ftrace it and see what kind of timers it is programming.
>> I've kept trying to narrow it down, and found out It's triggerable
>> using adjtimex().
Sorry, one more question: Could you provide details on how is it
trigger-able using adjtimex?
thanks
-john
next prev parent reply other threads:[~2012-08-06 18:22 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-24 17:10 rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6 Sasha Levin
2012-07-24 17:40 ` Paul E. McKenney
2012-07-24 20:55 ` Sasha Levin
2012-07-25 8:36 ` Michael Wang
2012-07-25 21:16 ` Sasha Levin
2012-07-26 5:10 ` Michael Wang
2012-07-25 9:06 ` Michael Wang
2012-07-26 11:42 ` Avi Kivity
2012-07-27 11:27 ` Sasha Levin
2012-07-29 12:48 ` Avi Kivity
2012-07-29 21:05 ` Sasha Levin
2012-07-30 5:36 ` Avi Kivity
2012-07-30 9:13 ` Sasha Levin
2012-07-30 9:33 ` Avi Kivity
2012-07-30 12:43 ` Sasha Levin
2012-07-30 13:17 ` Avi Kivity
2012-08-05 16:55 ` Sasha Levin
2012-08-06 17:21 ` John Stultz
2012-08-06 18:12 ` John Stultz
2012-08-06 18:20 ` John Stultz [this message]
2012-08-06 18:28 ` Sasha Levin
2012-08-06 20:31 ` John Stultz
2012-08-06 20:35 ` Sasha Levin
2012-08-07 5:05 ` Michael Wang
2012-08-07 5:40 ` John Stultz
2012-08-07 10:24 ` Sasha Levin
2012-08-08 2:20 ` Michael Wang
2012-08-06 19:24 ` Sasha Levin
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