Re: [PATCH] x86 - irq vector assignment
From: Thomas Gleixner
Date: Tue Sep 21 2010 - 17:43:50 EST
On Tue, 21 Sep 2010, Yinghai Lu wrote:
> > arch/x86/kernel/apic/io_apic.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > Index: linux/arch/x86/kernel/apic/io_apic.c
> > ===================================================================
> > --- linux.orig/arch/x86/kernel/apic/io_apic.c 2010-09-17 13:00:19.164638447 -0500
> > +++ linux/arch/x86/kernel/apic/io_apic.c 2010-09-17 13:00:23.448595373 -0500
> > @@ -3253,6 +3253,11 @@ unsigned int create_irq_nr(unsigned int
> > desc_new = move_irq_desc(desc_new, node);
> > cfg_new = desc_new->chip_data;
> >
> > +#ifdef CONFIG_NUMA
> > + if (node >= 0 && __assign_irq_vector(new, cfg_new, node_to_cpumask_map[node]) == 0)
> > + irq = new;
> > + else
> > +#endif
> > if (__assign_irq_vector(new, cfg_new, apic->target_cpus()) == 0)
> > irq = new;
> > break;
>
> target_cpus() for uv_x and x2apic phys mode all have cpu_online_mask()
>
> so we should get the vector for other cpus. aka __assign_irq_vector()
> should not fail. unless you have so many irq > nr_irqs.
Did you even read the changelog ? It's not about "should".
All CPU0 vectors are assigned already just because the current code
takes the first cpu in the target_cpus mask regardless of the node on
which the irq_desc is allocated. That's crap. Why do we allocate
irq_desc on node and leave the vector assigned to node(cpu0) ?
> current code we only make sure irq_desc on device local node.
Brilliant.
> for the vectors, user can set irq smp_affinity move the device local
> cpus if needed.
What a nonsense. If we allocate irq_desc on a target node it does not
make any sense to target the vector to whatever random node/cpu in the
first place and wait for user space to fix it up. What about running
into that situation _before_ we hit user space ?
Thanks,
tglx