Subject: Re: [PATCH v6 01/29] irq/matrix: Expose functions to allocate the best CPU for new vectors

From: Thomas Gleixner <[email-masked]>
Date: Fri, 06 May 2022 21:48:28 +0200

Ricardo,

On Thu, May 05 2022 at 16:59, Ricardo Neri wrote:
> Certain types of interrupts, such as NMI, do not have an associated vector.
> They, however, target specific CPUs. Thus, when assigning the destination
> CPU, it is beneficial to select the one with the lowest number of
> vectors.

Why is that beneficial especially in the context of a NMI watchdog which
then broadcasts the NMI to all other CPUs?

That's wishful thinking perhaps, but I don't see any benefit at all.

> Prepend the functions matrix_find_best_cpu_managed() and
> matrix_find_best_cpu_managed()

The same function prepended twice becomes two functions :)

> with the irq_ prefix and expose them for
> IRQ controllers to use when allocating and activating vector-less IRQs.

There is no such thing like a vectorless IRQ. NMIs have a vector. Can we
please describe facts and not pulled out of thin air concepts which do
not exist?

Thanks,

        tglx