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

[Mike Travis <travis@sgi.com>]

Eric W. Biederman wrote:
> Yinghai Lu <yhlu.kernel@gmail.com> writes:
> 
>> Please check dyn_array support for x86
> 
> YH you have not addressed any of my core concerns and this exceeds my review limit.
> Unfortunately I don't feel like this is a productive process.
> 
> My core concerns are:
> - You have not separated out and separately pushed the regression patch.  So that we can
>   fix the current rc release.  Simply tuning NR_IRQS is all I feel comfortable with for
>   fixing things in the post merge window period.
> 
> - The generic code has no business with dealing with NR_IRQS sized arrays.
>   Since we don't have a generic problem I don't see why we should have a generic dyn_array solution.
> 
> - The dyn_array infrastructure does not provide for per numa node allocation of
>   irq_desc structures, limiting NUMA scalability.
> 
> - You appear to be papering over problems instead of digging in and actually fixing them.
> 
> YH  Here is what I was suggesting when the topic of killing NR_IRQs came up a week or so
> ago.
> http://lkml.org/lkml/2008/7/10/439
> http://lkml.org/lkml/2008/7/10/532
> 
> Which essentially boils down to:
> - Removing NR_IRQS from the non-irq infrastructure code.
> - Add a config option for architectures that are not going to use an array
> - In the genirq code have a lookup function that goes from irq number to irq_desc *.
> 
> The rest we should be able to handle in a arch dependent fashion.
> 
> When we are done we should be able to create a stable irq number for msi interrupts
> that is something like:  bus:dev:fun:vector_no which is 8+5+3+12=28 bits long.
> 
> Eric

Hi Eric,

Small nit:  domain:bus:dev:fun:vector_no ... an SGI UV system can have potentially
512 domains (NODES), each having some # of busses.  

Thanks,
Mike