lkml.org 
[lkml]   [2012]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6
On 08/06/2012 11:28 AM, Sasha Levin wrote:
> On 08/06/2012 08:20 PM, John Stultz wrote:
>> 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?
> It triggers after a while of fuzzing using trinity of just adjtimex ('./trinity --quiet -l off -cadjtimex').
>
> Trinity is available here: http://git.codemonkey.org.uk/?p=trinity.git .
>
> Let me know if I can help further with reproducing this, I can probably copy over my testing environment to some other host if you'd like.
So far no luck. Dmesg mostly just gets filled up with trinity-child
OOMs. How much memory are you running with?

Are you running trinity as root or as some user that has CAP_SYS_TIME
and can actually change values via adjtimex? Or does it trip just by
reading the values?

thanks
-john




\
 
 \ /
  Last update: 2012-08-06 23:21    [W:0.077 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site