Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [patch] Add allowed_affinity to the irq_desc to make it possible to have restricted irqs | Date | Wed, 13 Dec 2006 13:06:12 -0700 |
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Ingo Molnar <mingo@elte.hu> writes:
> * Eric W. Biederman <ebiederm@xmission.com> wrote: > >> In addition the cases I can think of allowed_affinity is the wrong >> name. suggested_affinity sounds like what you are trying to implement >> and when it is merely a suggestion and not a hard limit it doesn't >> make sense to export like this. > > well, there are interrupts that must be tied to a single CPU and must > never be moved away. For example per-CPU clock-events-source interrupts > are such. So allowed_affinity very much exists.
Although in that case since it is a single cpu there is a much more elegant implementation. We don't need a full cpumask_t to describe it.
> also there might be hardware that can only route a given IRQ to a subset > of CPUs. While setting set_affinity allows the irqbalance-daemon to > 'probe' this mask, it's a far from optimal API.
I agree, I am just arguing that adding another awkward interface to the current situation does not really make the situation better, and it increases our support burden.
For a bunch of this it is arguable that the way to go is simply to parse the irq type in /proc/interrupts. All of the really weird cases will have a distinct type there. This certainly captures the MSI-X case. There is still a question of how to handle the NUMA case but...
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