From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 16 Feb 2006 17:34:22 +0100
From: Philippe Gerum <rpm@xenomai.org>
MIME-Version: 1.0
Subject: Re: [Xenomai-help] no-brainer realtime issue
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To: Steven Seeger <steve@domain.hid>
Cc: "xenomai@xenomai.org" <xenomai@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.