Re: [PATCH v3 4/5] genirq/affinity: allow driver's discontigous affinity set

[Ming Lei]

Hi Thomas,

On Mon, Jun 24, 2019 at 05:42:39PM +0200, Thomas Gleixner wrote:
> On Mon, 24 Jun 2019, Weiping Zhang wrote:
> 
> > The driver may implement multiple affinity set, and some of
> > are empty, for this case we just skip them.
> 
> Why? What's the point of creating empty sets? Just because is not a real
> good justification.

Patch 5 will add 4 new sets for supporting NVMe's weighted round robin
arbitration. It can be a headache to manage so many irq sets(now the total
sets can become 6) dynamically since size of anyone in the new 4 sets can
be zero, so each particular set is assigned one static index for avoiding
the management trouble, then empty set will be seen by
irq_create_affinity_masks().

So looks skipping the empty set makes sense because the API will become
easier to use than before.

Thanks,
Ming