[Xenomai] Slow execution of RT task

Philippe Gerum rpm at xenomai.org
Wed Apr 16 16:23:43 CEST 2014

On 04/16/2014 11:43 AM, Jeroen Van den Keybus wrote:
>> Could you patch the code fragment in, enable CONFIG_IPIPE_TRACE, then get a
>> dump from /proc/ipipe/trace/frozen once the warning has triggered?
>> Maybe getting a bit more context by setting
>> /proc/ipipe/trace/backtrace_points to 2048 would help too. TIA,
> I've attached the (somewhat lengthy) trace.
> BTW I now loaded xeno_nucleus and xeno_native in succession. The
> modprobing of xeno_native again locked until a new ssh terminal was
> opened (typing chars in the waiting ssh client didn't help).

 From that trace, it looks like an initial warning is issued on the same 
CPU, before the second one (i.e. rcutree.c:480) is raised:

:    #func               -2040	  0.088  print_oops_end_marker+0x0 
:    #func               -2040	  0.090  printk+0x0 
:|   #begin   0x80000001 -2040	  0.117  printk+0x66 

The trace backlog is not deep enough to locate the offending spot, but 
the lines above typically close a WARN_ON() handling. Once this first 
warning is sent out, the CPU then waits for 2s before receiving a timer 
IRQ from the APIC:

:    #func               -2032! 1998.529  intel_idle+0x0 
:|   #begin   0x000000ef   -34	  0.097  apic_timer_interrupt+0x6d 

Could you check your kernel logs for this initial warning? Maybe this 
would shed light, assuming the second bug may be a side-effect of the 
first one.



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