linux-kernel - Re: [PATCH] x86 - irq vector assignment

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Message-ID: <20100921235312.GA3514@sgi.com>
Date:	Tue, 21 Sep 2010 18:53:12 -0500
From:	Jack Steiner <steiner@....com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, mingo@...e.hu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86 - irq vector assignment

On Tue, Sep 21, 2010 at 04:12:33PM -0700, Yinghai Lu wrote:
> On 09/21/2010 02:34 PM, Thomas Gleixner wrote:
> > 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) ?
> 
>  ok, i got it. vectors from cpus on node0 are used by devices from others nodes.
> later devices from node0 can not get vector from node0.

Does that resolve all of your questions or are there still other issues.


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