Re: [Xenomai-help] no-brainer realtime issue

[Philippe Gerum <rpm@xenomai.org>]

Steven Seeger wrote:
> I have a xenomai userspace application that does the following:
> 
> A thread of priority 90 toggles a bit (outb) to move a stepper motor.
> 
> A thread of priority 10 updates the display once a second.
> 
> The motor thread is periodic and uses rt_task_wait_period(). The display
> thread just uses sleep(1).
> 
> My question is this: the priority 90 thread is higher priority, and doesn't
> do anything relating to linux system calls. Whenever the display thread
> updates the display, the motor thread stalls momentarily.

X-window graphic card driver masking hw IRQs? You should see that too when running 
the latency tests while moving windows around the desktop.

Btw, how to you measure/observe the stalled state?

> 
> Any idea why this is?
> 
> Steven
> 
> 
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-- 

Philippe.