Set irq affinity from a user mode task.

Set irq affinity from a user mode task.

[Tamás Paál]

Dear all!

I am using Xenomai_3.2.1 on x86.
Is there a way to set the IRQ CPU affinity of the rt_e1000e Ethernet
driver from my user mode xenomai application? (I mean without
modifying and rebuilding the driver.)

Thank you,
Tamas

RE: Set irq affinity from a user mode task.

[Chen, Hongzhan]

It seems that the community  discussed such thing long time ago as in https://xenomai.org/pipermail/xenomai/2017-November/037914.html . According to discussion,  it should provide generic API to set irq affinity for CAN, rtnet, uarts, SPI etc. But I can not find any code
using rtdm_cpumask_t under include/rtdm/*.  I do not know what block its implementation.

Regards

Hongzhan Chen

>-----Original Message-----
>From: Tamás Paál <paal.tam@gmail.com>
>Sent: Friday, June 9, 2023 3:41 PM
>To: xenomai@lists.linux.dev
>Subject: Set irq affinity from a user mode task.
>
>Dear all!
>
>I am using Xenomai_3.2.1 on x86.
>Is there a way to set the IRQ CPU affinity of the rt_e1000e Ethernet
>driver from my user mode xenomai application? (I mean without
>modifying and rebuilding the driver.)
>
>Thank you,
>Tamas

Re: Set irq affinity from a user mode task.

[Jan Kiszka]

On 12.06.23 03:28, Chen, Hongzhan wrote:
> 
> It seems that the community  discussed such thing long time ago as in https://xenomai.org/pipermail/xenomai/2017-November/037914.html . According to discussion,  it should provide generic API to set irq affinity for CAN, rtnet, uarts, SPI etc. But I can not find any code
> using rtdm_cpumask_t under include/rtdm/*.  I do not know what block its implementation.

Someone has to take action, I would say.

But I would rather suggest that we check if Dovetail needs changes so
that affinity is tunable via proc, just like for Linux IRQs. Maybe that
even works already, don't recall ATM. In any case, IRQ affinities are
generally not application topics, rather system integrator tasks.

Jan

-- 
Siemens AG, Technology
Competence Center Embedded Linux

RE: Set irq affinity from a user mode task.

[Chen, Hongzhan]

>-----Original Message-----
>From: Jan Kiszka <jan.kiszka@siemens.com>
>Sent: Monday, June 12, 2023 3:54 PM
>To: Chen, Hongzhan <hongzhan.chen@intel.com>; Tamás Paál
><paal.tam@gmail.com>; xenomai@lists.linux.dev
>Subject: Re: Set irq affinity from a user mode task.
>
>On 12.06.23 03:28, Chen, Hongzhan wrote:
>>
>> It seems that the community  discussed such thing long time ago as in
>https://xenomai.org/pipermail/xenomai/2017-November/037914.html .
>According to discussion,  it should provide generic API to set irq affinity for
>CAN, rtnet, uarts, SPI etc. But I can not find any code
>> using rtdm_cpumask_t under include/rtdm/*.  I do not know what block its
>implementation.
>
>Someone has to take action, I would say.
>
>But I would rather suggest that we check if Dovetail needs changes so
>that affinity is tunable via proc, just like for Linux IRQs. Maybe that
>even works already, don't recall ATM. In any case, IRQ affinities are
>generally not application topics, rather system integrator tasks.

Yes, you are right. Under Dovetail, we can modify /proc/irq/irqnumber/smp_affinity
to set irq affinity. I verified that it works for rt_igb.

Regards

Hongzhan Chen



>
>Jan
>
>--
>Siemens AG, Technology
>Competence Center Embedded Linux