Re: [PATCH v5 5/7] iommu/dma: Allow a single FQ in addition to per-CPU FQs

[Jason Gunthorpe]

On Mon, Jan 30, 2023 at 04:57:56PM +0100, Niklas Schnelle wrote:

> I'm wondering if maybe instead of plain flag bits it makes more sense
> to have a dma_iommu_options struct that contains the queue size and a
> flags value which indicates whether a single or per-CPU queue is
> used.

Querying the driver for what kind of performance tuning it would like
to use by default makes sense to me.

> Then I could add an iommu_ops callback that takes a device and a
> pointer to the dma_iommu_options. That way we can still set the options
> per device but don't need a whole extra domain type. This callback
> would then just be called during initialization of the DMA-FQ domain
> and not having the callback just leaves the defaults unchanged. Does
> that go in the right direction?

I like it

Jason