Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for custom page providers

[Jason Gunthorpe]

On Fri, Jun 07, 2024 at 08:27:29AM -0600, David Ahern wrote:
> On 6/7/24 7:42 AM, Pavel Begunkov wrote:
> > I haven't seen any arguments against from the (net) maintainers so
> > far. Nor I see any objection against callbacks from them (considering
> > that either option adds an if).
> 
> I have said before I do not understand why the dmabuf paradigm is not
> sufficient for both device memory and host memory. A less than ideal
> control path to put hostmem in a dmabuf wrapper vs extra checks and
> changes in the datapath. The former should always be preferred.

I think Pavel explained this - his project is principally to replace
the lifetime policy of pages in the data plane. He wants to change
when a page is considered available for re-allocation because
userspace may continue to use the page after the netstack thinks it is
done with it. It sounds like having a different source of the pages is
the less important part.

IMHO it seems to compose poorly if you can only use the io_uring
lifecycle model with io_uring registered memory, and not with DMABUF
memory registered through Mina's mechanism.

Jason