Re: rcu self-detected stall messages on OMAP3, 4 boards

[Frederic Weisbecker]

2012/9/22 Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>:
> On Fri, Sep 21, 2012 at 01:31:49PM -0700, Tony Lindgren wrote:
>> * Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> [120921 12:58]:
>> >
>> > Just to make sure I understand the combinations:
>> >
>> > o   All stalls have happened when running a minimal userspace.
>> > o   CONFIG_NO_HZ=n suppresses the stalls.
>> > o   CONFIG_RCU_FAST_NO_HZ (which depends on CONFIG_NO_HZ=y) has
>> >     no observable effect on the stalls.
>>
>> The reason why you may need minimal userspace is to cut down
>> the number of timers waking up the system with NO_HZ.
>> Booting with init=/bin/sh might also do the trick for that.
>
> Good point!  This does make for a very quiet system, but does not
> reproduce the problem under kvm, even after waiting for four minutes.
> I will leave it for more time, but it looks like I really might need to
> ask Linaro for remote access to a Panda.

I have one. I'm currently installing Ubuntu on it and I'll try to
manage to build
a kernel and reproduce the issue.

I'll give more news soon.
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