Re: [Xenomai-core] Frozen timer IRQ

[Philippe Gerum <rpm@xenomai.org>]

Jan Kiszka wrote:
> Philippe Gerum wrote:
> 
>>Jan Kiszka wrote:
>>
>>>Philippe Gerum wrote:
>>>
>>>
>>>>Jan Kiszka wrote:
>>>>
>>>>
>>>>>Attached is an ipipe-freeze of the frozen system. It's taken at the
>>>>>time
>>>>>the main thread of the terminating application has successfully
>>>>>rt_task_join'ed the last remaining RT-thread. I took 2000 trace points
>>>>>before and after that point and additionally instrumented
>>>>>rthal_timer_program_shot() (special trace 0x01, the argument is the
>>>>>delay). The interesting stuff happens around 600 us after the
>>>>>freeze: it
>>>>>seems the scheduled Linux timer arrives then but doesn't get much
>>>>>attention beyond from ipipe.
>>>>>
>>>>>Any idea what to look for next? I have a "perfect" test system now,
>>>>>though I still see no light at the end of the tunnel how to export
>>>>>it to
>>>>>other boxes.
>>>>>
>>>>>Enough for today.
>>>>>
>>>>>Jan
>>>>>
>>>>>
>>>>>PS: This trace was taken over 2.6.15 to exclude any issues with the new
>>>>>2.6.16. Both kernels show the same effect.
>>>>>
>>>>
>>>>Does this patch make any difference?
>>>>
>>>>--- ipipe-root.c~    2006-01-31 09:55:44.000000000 +0100
>>>>+++ ipipe-root.c    2006-04-06 17:01:49.000000000 +0200
>>>>@@ -328,9 +328,8 @@
>>>>        /* Only sync virtual IRQs here, so that we don't recurse
>>>>           indefinitely in case of an external interrupt flood. */
>>>>
>>>>-        if ((ipipe_root_domain->cpudata[cpuid].
>>>>-             irq_pending_hi & IPIPE_IRQMASK_VIRT) != 0)
>>>>-            __ipipe_sync_stage(IPIPE_IRQMASK_VIRT);
>>>>+        if (ipipe_root_domain->cpudata[cpuid].irq_pending_hi != 0)
>>>>+            __ipipe_sync_stage(IPIPE_IRQMASK_ANY);
>>>>    }
>>>>#ifdef CONFIG_IPIPE_TRACE_IRQSOFF
>>>>    ipipe_trace_end(0x8000000D);
>>>
>>>
>>>Nope.
>>
>>That's good news, actually. I would have been quite embarrased if it did
>>it.
>>
>>
>>>Where should I put my finger on to find out what's happening?
>>>
>>
>>It seems that the pipeline log is not synced by __ipipe_unstall_iret_root.
>>We need to know why. Question: is the root stage stalled or unstalled by
>>this
>>routine during the latest call before the box freezes?
> 
> 
> I'm currently switching my brain between to many tasks: Could you simply
> tell me what variable to check so that I can hack some
> ipipe_trace_special into the kernel?

The value of the IPIPE_STALL_FLAG for the root domain upon exit from 
__ipipe_unstall_iret_root.

> 
> 
>>PS: it would be nice to display the status of the current stage
>>(stalled/unstalled) and the one of the hw interrupt bit, for each trace.
> 
> 
> Patches are welcome :) - wait, you are the Adeos maintainer! ;)
> 
> Actually, the hw-irq state is already expressed by "|" at the head of
> each line ("|" means "hw-IRQs off").
> 

Ok, I'm rather short in time too, so let's drop this for now and keep it 
on the todo list so that we get back to this when time allows.

-- 

Philippe.