From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Sat, 15 Jul 2006 13:28:54 +0800
From: Liu Zhenghui <ferretliu@domain.hid>
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Subject: [Xenomai-help] Different performance in irq handling between native
	skin and rtdm?
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I have an A/D card which has a shared irq number 16 with the Radeon 7500
video card. So I have to in isr tell whether this interrupt is from AD
card. If not, then let other isr handle it. For native skin, this is
done by returning RT_INTR_PROPAGATE in isr, while for rtdm, by using
RTDM_IRQTYPE_SHARED flag when request the interrupt. I found both works,
but rtdm solution make the xorg very slow (open a new window, animation
etc.), while native skin not. It seems that it take a much longer
latency for rtdm to propagate the irq to video card than for native
skin. How did this happen?

My xenomai version is 2.1.0, linux kernel is 2.6.15.7

* The simplest codes for native skin is like following:

  RT_INTR AD_intr;

  err=rt_intr_create(&AD_intr, "ADISR", 16, AD_ISR, NULL, 0);

  err=rt_intr_enable(&AD_intr);

And in the cleanup function:

  rt_intr_delete(&AD_intr);

And the ISR:

  int AD_ISR(struct xnintr *intr)
  {
	if(AD_IS_IRQ){  //A macro to know whether it's an AD card IRQ
        	
		//do some thing

		//the returned value tell RTAI IRQ is done
		return (RT_INTR_HANDLED);
	}
	else{
		//this IRQ is not AD card IRQ
		//the returned value let linux to handle such IRQ
		return (RT_INTR_NONE | RT_INTR_PROPAGATE);
	}
  }


* The simplest codes for rtdm is like following:

  rtdm_irq_t AD_intr;

  err = rtdm_irq_request(&AD_intr, 16, AD_ISR, RTDM_IRQTYPE_SHARED, 		
			  ADISR", NULL);

  err = rtdm_irq_enable(&AD_intr);

And in the cleanup function:

  rtdm_irq_free(&AD_intr);

And the ISR:

  static int AD_ISR(rtdm_irq_t *irq_handle)
  {
	if(AD_IS_IRQ){  //A macro to know whether it's an AD card IRQ
        	
		//do some thing

		//the returned value tell RTAI IRQ is done
		return (RTDM_IRQ_HANDLED);
	}
	else{
		//this IRQ is not AD card IRQ
		//the returned value let linux to handle such IRQ
		return (RTDM_IRQ_NONE);
	}

  }


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