Re: [PATCH 00/16] dyn_array and nr_irqs support v2

[Eric W. Biederman]

"Yinghai Lu" <yhlu.kernel@xxxxxxxxx> writes:

> On Fri, Aug 1, 2008 at 2:30 PM, Yinghai Lu <yhlu.kernel@xxxxxxxxx> wrote:
>> On Fri, Aug 1, 2008 at 1:46 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> wrote:
>
>>> http://lkml.org/lkml/2008/7/10/439
>
> you moved kstat_irqs to irqdesc, and it will not numa-aware. if
> irq_desc is not go with every cpu.

That part is a limitation of the per cpu allocator that the sgi guys
are in the process of fixing.  Which is one of the following goals
of folding the pda into a per cpu structure.

In practice it matters little as irqs only occur on one cpu at a time,
so we shouldn't have cache line contention.

I never got to the arch specific part of allocating irq_desc in a numa
aware fashion.  But I have always figured that if we move the work to
arch code it won't be too difficult, to do things appropriately.

Eric
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