[Xenomai-help] RE : IRQ latency
Hi,
I installed xenomai on an overo water board (cortex A8) and performed
latency tests.
What version of Xenomai?
I tested two modules.
The first module is based on an internal timer. It toggles a GPIO each
1ms.
The second module waits for an external interrupt from an input GPIO
(square signal at 1KHz). When that happens, the module toggles a GPIO pin.
When i load the system and do a transfer from Ethernet to the sd card the
first module works fine with a maximum latency less than 50us.
But the second module, in the same context, have a maximum latency of
several milliseconds.
As the first module works fine i think i have a problem with the hardware
configuration like the hardware irq priority.
In the irq.c file, the irq priority level is not set for the linux domain.
Should i configure the irq level at the initialization of the board ? What
else could cause this issue ?
The error is more likely in the code of your driver. Show us the code.
Hi Gilles,
Sorry, i forgot the essential.
My linux kernel version is the 2.6.38 from sakoman.
My xenomai version is xenomai-2.6.0
The adeos patch is : adeos-ipipe-2.6.38.8-arm-1.18-04.patch (
./prepare-kernel.sh --linux=${WORKDIR}/git --arch=arm
--adeos=${WORKDIR}/xenomai-2.6.0/ksrc/arch/arm/patches/adeos-ipipe-2.6.38.8-arm-1.18-04.patch).
The xenomai user space is make with the next configuration :
./configure --build=arm-ti-linux --host=arm-none-linux-gnueabi --prefix=/usr
--includedir=/usr/include/xenomai --enable-arm-tsc=omap3 --disable-dox-doc
--disable-dbx LDFLAGS=-Wl,-O1 -Wl,--hash-style=gnu
The module code is :
For the init of the module:
-
if (!(((gpio_request(RX_TST_GPIO,RX_TST_GPIO) == 0)
(gpio_direction_input(RX_TST_GPIO) == 0 {
rtdm_printk(KERN_DEBUG Could not claim GPIO for
TX_SPACE_AVAILABLE_GPIO\n);
erreur_return |= 1;
return -1;
}
if (!(((gpio_request(TX_TST_GPIO,RX_TST_GPIO) == 0)
(gpio_direction_output(TX_TST_GPIO,0) == 0 {
rtdm_printk(KERN_DEBUG Could not claim GPIO for
TX_SPACE_AVAILABLE_GPIO\n);
erreur_return |= 2;
return -1;
}
ret = request_irq(gpio_to_irq(RX_TST_GPIO),
space_available_irqhandler,
IRQF_TRIGGER_FALLING|IRQF_DISABLED, usrp_intr_aviable, NULL);
if((ret!=0)){ rtdm_printk(KERN_DEBUG Could not request irq\n);
erreur_return |= 4;}
disable_irq(gpio_to_irq(RX_TST_GPIO));
free_irq(gpio_to_irq(RX_TST_GPIO), NULL);
err = rtdm_irq_request(rt_irq_handle, gpio_to_irq(RX_TST_GPIO),
rt_data_ready_irqhandler, RTDM_IRQTYPE_EDGE, XENO_IRQ_RECEIVE,NULL);
err = rtdm_irq_enable(rt_irq_handle);
The irq code is:
-
static int rt_data_ready_irqhandler(rtdm_irq_t *irq_handle)
{
iomask ^= 1;
gpio_set_value(TX_TST_GPIO, iomask);
return RTDM_IRQ_HANDLED;
}
Thanks for your help.
JP
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Re: [Xenomai-help] RE : IRQ latency
On 05/18/2012 09:06 AM, Jean-Pascal JULIEN wrote:
Hi,
I installed xenomai on an overo water board (cortex A8) and performed
latency tests.
What version of Xenomai?
I tested two modules.
The first module is based on an internal timer. It toggles a GPIO each
1ms.
The second module waits for an external interrupt from an input GPIO
(square signal at 1KHz). When that happens, the module toggles a GPIO pin.
When i load the system and do a transfer from Ethernet to the sd card the
first module works fine with a maximum latency less than 50us.
But the second module, in the same context, have a maximum latency of
several milliseconds.
As the first module works fine i think i have a problem with the hardware
configuration like the hardware irq priority.
In the irq.c file, the irq priority level is not set for the linux domain.
Should i configure the irq level at the initialization of the board ? What
else could cause this issue ?
The error is more likely in the code of your driver. Show us the code.
Hi Gilles,
Sorry, i forgot the essential.
My linux kernel version is the 2.6.38 from sakoman.
My xenomai version is xenomai-2.6.0
The adeos patch is : adeos-ipipe-2.6.38.8-arm-1.18-04.patch (
./prepare-kernel.sh --linux=${WORKDIR}/git --arch=arm
--adeos=${WORKDIR}/xenomai-2.6.0/ksrc/arch/arm/patches/adeos-ipipe-2.6.38.8-arm-1.18-04.patch).
The xenomai user space is make with the next configuration :
./configure --build=arm-ti-linux --host=arm-none-linux-gnueabi --prefix=/usr
--includedir=/usr/include/xenomai --enable-arm-tsc=omap3 --disable-dox-doc
--disable-dbx LDFLAGS=-Wl,-O1 -Wl,--hash-style=gnu
You do not need --enable-arm-tsc.
I see nothing wrong with your code. However this version of the I-pipe
patch has a bug with gpio irqs. You can try backporting this patch:
http://git.xenomai.org/?p=ipipe-gch.git;a=commit;h=81bfc05c4716b76e79f5e486baf4c52015a3b92c
To fix it. If that is the cause of your problem, then you should only
see the bug if you are running some other real-time program which
triggers a user-space task wakeup based in an interrupt, such as for
instance the timer interrupt. Running the latency test for instance
would do that.
--
Gilles.
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