Re: [Xenomai] Xenomai installation on P1020RDB

[Philippe Gerum <rpm@xenomai.org>]

On 07/27/2012 06:12 PM, Lukasz Zemla wrote:
>
>> -----Original Message-----
>> From: Philippe Gerum [mailto:rpm@xenomai.org]
>> Sent: Friday, July 27, 2012 6:09 PM
>> To: Gilles Chanteperdrix
>> Cc: Lukasz Zemla; Xenomai@xenomai.org
>> Subject: Re: [Xenomai] Xenomai installation on P1020RDB
>>
>> On 07/27/2012 06:00 PM, Gilles Chanteperdrix wrote:
>>> On 07/27/2012 05:53 PM, Lukasz Zemla wrote:
>>>
>>>> What I discovered, the source of the '76s problem' could be
>> preemption model. Now, when I set:
>>>>    - CONFIG_PREEMPT - the lag exists exactly after eth0
>> initialization.
>>>>    - CONFIG_PREEMPT_VOLUNTARY - the boot process stops for a while
>> (about 50-70s) in different places.
>>>>    - CONFIG_PREEMPT_NONE then all is fine, I cannot observe any
>> described problems.
>>>
>>>
>>> CONFIG_PREEMPT or PREEMPT_VOLUNTARY. Try this patch:
>>>
>>> diff --git a/arch/powerpc/kernel/ipipe.c
>> b/arch/powerpc/kernel/ipipe.c
>>> index 45302c1..5b706da 100644
>>> --- a/arch/powerpc/kernel/ipipe.c
>>> +++ b/arch/powerpc/kernel/ipipe.c
>>> @@ -344,8 +344,10 @@ static void __ipipe_do_IRQ(unsigned int irq,
>> void
>>> *cookie)
>>>
>>>    static void __ipipe_do_timer(unsigned int irq, void *cookie)
>>>    {
>>> +	irq_enter();
>>>    	check_stack_overflow();
>>>    	timer_interrupt(__this_cpu_ptr(&ipipe_percpu.tick_regs));
>>> +	irq_exit();
>>>    }
>>>
>>>    asmlinkage int __ipipe_grab_timer(struct pt_regs *regs)
>>>
>>> Or to remove the #ifdef CONFIG_IPIPE / #endif around the calls to
>>> irq_enter/irq_exit in arch/powerpc/kernel/time.c
>>>
>>
>> Mm, no. On ppc, we use a virtual irq to map the decrementer, so the
>> pipeline core already took care of marking the irq entry before calling
>> the __ipipe_do_timer handler. The issue may be in the log syncer
>> instead.
>
> Maybe I have some symptom which I forgot to write. When the system with CONFIG_PREEMPT stayed unused for last night I saw following errors:

I should be able to reproduce this issue on some hw I have access to. 
I'll have a look and let you know. Thanks.

>
> Yocto (Built by Poky 6.0) 1.1 p1020rdb ttyS0
>
> p1020rdb login: [  193.919436] INFO: rcu_preempt detected stalls on CPUs/tasks: { 1} (detected by 0, t=15002 jiffies)
> [  193.928407] Call Trace:
> [  193.930860] [c0799cb0] [c0008234] show_stack+0x4c/0x174 (unreliable)
> [  193.937222] [c0799cf0] [c0092464] __rcu_pending+0x424/0x440
> [  193.942794] [c0799d30] [c0092a84] rcu_check_callbacks+0x150/0x1f8
> [  193.948893] [c0799d50] [c0056f40] update_process_times+0x3c/0x60
> [  193.954904] [c0799d70] [c0079fe4] tick_sched_timer+0x8c/0xfc
> [  193.960570] [c0799da0] [c006bdb4] __run_hrtimer.isra.28+0x58/0x100
> [  193.966751] [c0799dc0] [c006cc3c] hrtimer_interrupt+0x160/0x408
> [  193.972673] [c0799e50] [c0009d14] timer_interrupt+0x13c/0x1b8
> [  193.978421] [c0799e80] [c000e2cc] __ipipe_do_timer+0x44/0x54
> [  193.984082] [c0799e90] [c009467c] __ipipe_do_sync_stage+0x1e0/0x220
> [  193.990350] [c0799ec0] [c000e9a0] __ipipe_grab_timer+0xa8/0xc0
> [  193.996186] [c0799ed0] [c00107a4] __ipipe_ret_from_except+0x0/0xc
> [  194.002282] --- Exception: 901 at cpu_idle+0x8c/0xf0
> [  194.002286]     LR = cpu_idle+0x8c/0xf0
> [  194.011067] [c0799f90] [c0008df8] cpu_idle+0xb0/0xf0 (unreliable)
> [  194.017165] [c0799fb0] [c0002438] rest_init+0x88/0x98
> [  194.022221] [c0799fc0] [c072778c] start_kernel+0x2e8/0x2fc
> [  194.027706] [c0799ff0] [c00003fc] skpinv+0x2e8/0x324
> [ 6662.479437] INFO: rcu_bh detected stalls on CPUs/tasks: { 1} (detected by 0, t=15002 jiffies)
> [ 6662.487975] Call Trace:
> [ 6662.490428] [c0799cb0] [c0008234] show_stack+0x4c/0x174 (unreliable)
> [ 6662.496790] [c0799cf0] [c0092464] __rcu_pending+0x424/0x440
> [ 6662.502363] [c0799d30] [c0092a68] rcu_check_callbacks+0x134/0x1f8
> [ 6662.508460] [c0799d50] [c0056f40] update_process_times+0x3c/0x60
> [ 6662.514473] [c0799d70] [c0079fe4] tick_sched_timer+0x8c/0xfc
> [ 6662.520138] [c0799da0] [c006bdb4] __run_hrtimer.isra.28+0x58/0x100
> [ 6662.526319] [c0799dc0] [c006cc3c] hrtimer_interrupt+0x160/0x408
> [ 6662.532241] [c0799e50] [c0009d14] timer_interrupt+0x13c/0x1b8
> [ 6662.537989] [c0799e80] [c000e2cc] __ipipe_do_timer+0x44/0x54
> [ 6662.543650] [c0799e90] [c009467c] __ipipe_do_sync_stage+0x1e0/0x220
> [ 6662.549917] [c0799ec0] [c000e9a0] __ipipe_grab_timer+0xa8/0xc0
> [ 6662.555752] [c0799ed0] [c00107a4] __ipipe_ret_from_except+0x0/0xc
> [ 6662.561849] --- Exception: 901 at cpu_idle+0x8c/0xf0
> [ 6662.561852]     LR = cpu_idle+0x8c/0xf0
> [ 6662.570635] [c0799f90] [c0008df8] cpu_idle+0xb0/0xf0 (unreliable)
> [ 6662.576732] [c0799fb0] [c0002438] rest_init+0x88/0x98
> [ 6662.581788] [c0799fc0] [c072778c] start_kernel+0x2e8/0x2fc
> [ 6662.587273] [c0799ff0] [c00003fc] skpinv+0x2e8/0x324
>


-- 
Philippe.