Re: [Xenomai-help] awful latencies (~110us)

["CHABAL David" <david.chabal@domain.hid>]

Jan Kiszka a écrit :
> CHABAL David wrote:
>> Philippe Gerum a écrit :
>>> I suspect the tracer to induce massive cache misses on your setup, which
>>> limits the interpretation we can have of this log. Could you apply the
>>> following patch, and post back the frozen log for the very same test?
>>> TIA,
>>>
>>> --- 2.6.20-ipipe-1.8-08/kernel/ipipe/core.c~    2007-09-16
>>> 16:54:34.000000000 +0200
>>> +++ 2.6.20-ipipe-1.8-08/kernel/ipipe/core.c    2007-10-10
>>> 13:05:28.000000000 +0200
>>> @@ -283,7 +283,7 @@
>>>      unsigned long flags;
>>>      int s;
>>>  
>>> -    local_irq_save_hw(flags);
>>> +    local_irq_save_hw_notrace(flags);
>>>      __raw_spin_lock(lock);
>>>      ipipe_load_cpuid();
>>>      ipd = per_cpu(ipipe_percpu_domain, cpuid);
>>> @@ -302,7 +302,7 @@
>>>      ipd = per_cpu(ipipe_percpu_domain, cpuid);
>>>      if (!raw_demangle_irq_bits(&x))
>>>          __clear_bit(IPIPE_STALL_FLAG, &ipd->cpudata[cpuid].status);
>>> -    local_irq_restore_hw(x);
>>> +    local_irq_restore_hw_notrace(x);
>>>  }
>>>  
>>>  /*
>>>
>> The freeze file enclosed is generated with this patch and the i8259.c
>> patch.
>>
>> ---|------------|------------|------------|--------|-------------------------
>>
>> RTS|       5.570|       9.400|      85.356|       0|    00:08:55/00:08:55
>>
>> Should I try without the I-pipe debugger ?
> 
> Never say never, but the tracer most probably not causing these
> latencies. Currently, all points to the good-old programmable interrupt
> controller.
> 
> Do you have CONFIG_X86_UP_IOAPIC enabled? If no, please try to do so.
> 
> Jan
> 
Yes, I did it.