[Xenomai] xenomai , irq and pci

[Johann Obermayr <johann.obermayr@sigmatek.at>]

Hello,

celeron dual core with PCIe - PCI bridge
we use kernel 3.10.xx smp with  (isolcpus=0)
smi is disabled.
xenomai 2.6.3

we have a pci card with a fpga (with irq) and sram.

we have 2 task running.

task0 is one high prior in primary domain on core0.
this task wait for event, that is fired by fpga irq.
than this task will make some pci accesses to the fpga.

the other task (task1) is a shadow task, but running in secondary domain 
on core 1.
This task make many big memcpy to sram.

in the ipipe_handler_irq we have a function callback.
a small driver hooks to this callback add make some tracepoint into
a shared memory.

with the trace we see some time a very high jitter in the ipipe_handler_irq
function (around 250 us).
has anyone an explanation for this?

and a 4 byte access from task0 to fpga need more than 300us,
  while task1 is writing to sram.

Thanks
   Johann